LOS ANGELES, MAY 9 -- When outnumbered police officers retreated in confusion from Florence and Normandie avenues April 29, they did not realize that the skirmish they were conceding to angry street gangs was the opening battle of what would become modern America's most deadly urban riot.

"We thought we were beating a tactical retreat and would return in force," said an officer in the first unit ordered to leave the flashpoint. "We didn't know we were abandoning the community."

Police never regrouped to take control of the vital and violent intersection, an action that Police Chief Daryl F. Gates concedes was a serious mistake. Quickly, the carnage escalated and spread. By the time it ended, at least 53 people had died, at least 2,300 had been injured, more than 16,000 were under arrest and thousands of buildings had been burned and looted.

"It was the Pearl Harbor of the LAPD," City Council member Zev Yaroslavsky said, using a metaphor that even high-ranking Los Angeles Police Department officers privately agree is apt. As in the notorious Japanese attack that destroyed much of the U.S. Pacific fleet in 1941, early warnings were ignored, dangers underestimated and communications confused. As at Pearl Harbor, low-ranking individuals responded bravely while their leaders issued conflicting orders and often seemed paralyzed by indecision.

Lt. Michael Moulin of the 77th Street Division, the man in charge at Florence and Normandie, said this week that he ordered 25 officers to withdraw from there because "I didn't want them killed." Three of the officers, interviewed by The Washington Post under condition of anonymity, said they thought that they would be brought back in a larger force to arrest ringleaders and halt the disturbances.

But, for reasons not yet certain, the larger force never materialized. Officer Bob Avina, a member of a special weapons and tactics team, said "hundreds" of police were mobilized at a command post at 54th Street and Arlington Avenue, less than three miles away, but not sent into battle at Florence and Normandie.

While officers fretted about the delay, the reinforcements were held at the command post for more than an hour before being dispersed to other locations as violence spread throughout the 7-by-15-mile area known as south-central Los Angeles. {See map on Page A23}

Officers ordered to withdraw by Moulin were hesitant to echo widespread criticism of Gates, who had left his downtown command center to attend a political fund-raiser during the early hours of the riots. One officer called Gates, who is to leave office next month, "a lame duck who has been pushed out by the politicians." Two of the unnamed officers said Mayor Tom Bradley's denunciation of the verdict virtually exonerating four white officers charged with beating black motorist Rodney G. King may have encouraged rioters.

But all three said violence might have been contained quickly had LAPD been able to muster massive force at Florence and Normandie, where motorists were being dragged from vehicles and beaten. Helicopters hired by local television stations hovered, bringing the violence live to millions of Southern Californians and sending a message to potential looters and arsonists that police were not in control.

The LAPD motto is "To Protect and Serve," but officers lost control after the verdict. Although Bradley and Stanley K. Sheinbaum, president of the Police Commission, said Gates assured them that he had contingency plans for dealing with any emergency arising from acquittals in the King case, officers on their own early in the crisis said they were unaware of specific plans.

Bradley and Yaroslavsky were among civic and community leaders gathered on the evening of the verdict at First African Methodist Episcopal Church for a rally aimed at urging residents to protest peacefully.

By the time the rally ended at 8 o'clock Pacific time, just after sunset, violence had spread near the church where several cars, including Yaroslavsky's, were looted and destroyed while Bradley spoke inside. By the next morning, nearby apartments had been burned and a commercial building looted. But the church, the city's oldest black house of worship, was spared throughout the riots.

Although Gates declared on national television last Sunday that he had not known when the verdict was coming, prosecution and defense attorneys had forecast accurately that jurors would reach a decision within seven to 10 days. They did so in seven days.

While the jury was sequestered, Superior Court Judge Stanley M. Weisberg told attorneys for both sides that, when jurors told him they had reached a verdict, he would wait two hours before expecting both sides in court. The delay was intended to give everyone time to reach the remote courthouse in Simi Valley but also provided LAPD commanders an early warning that went unheeded.

At 1 p.m. Pacific time, court officials told attorneys, Ventura County sheriff's deputies and the LAPD that verdicts would be announced in two hours. At 3:15 p.m., verdicts acquitting three officers and virtually exonerating the fourth were read live on television, and many LAPD officers were surprised. Throughout the city, they were completing their day shifts.

"Had we prepared for the worst when we knew the jury had reached a verdict, we could have kept hundreds of officers on duty," said one officer critical of the slow response. Gates: 'Mistakes Were Made'

Instead, most day-shift officers left at 4 p.m. after regular eight-hour tours. Many were heading home even as street-gang members were meeting at an abandoned house near Florence and Normandie to plan their violent course. Not until the next day, when the conflagration was out of control, would the entire 8,300-member LAPD be placed on two 12-hour shifts.

Gates himself is critical of the initial response. "Mistakes were made," he said this week.

On Friday, Gates acknowledged to reporters that a tactical alert putting the entire department on emergency footing should have been declared sooner. He also implicitly criticized Moulin, not for withdrawing police from Florence and Normandie but for failing to return there in greater force. "I guess in the heat of the situation, memory fails," Gates said. "Sometimes you don't react as you ought to. Sometimes you panic, and sometimes a little bit of paralysis sets in."

But the chief's critics said the mistakes and paralysis began with Gates, privately described by other high-ranking LAPD officers as detached from the nuts-and-bolts of police work after 14 years in his post, which carries civil service job protection. "The top leadership of the department was in disarray," said Warren M. Christopher, former U.S. deputy secretary of state and a prominent attorney who headed the commission that investigated the department and recommended reforms after the King beating last year.

Most of the LAPD leadership was not even present in the Emergency Command Center downtown when seemingly incidental violence at Florence and Normandie escalated into full-scale rioting.

The first complaint was received at the department's 77th Street Division at 5:25 p.m. when youths began throwing beer cans at motorists in the intersection. Police responded and took a black man into custody, but they departed after a sidewalk shoving match.

At 6:30 p.m., Gates left police headquarters in the downtown Parker Center for Brentwood, an upscale west side community, to make a speech opposing a June 2 ballot initiative that would limit Los Angeles police chiefs to two five-year terms. He concedes that he should not have departed then.

The chief left behind a Parker Center command post from which the LAPD's other highest-ranking officers were absent. Assistant Chief Robert Vernon, described by insiders as the man who has run the department for the last year and who is retiring soon, was headed for a Florida vacation. When Vernon reached his destination and offered to return, he said, he was told that he was not needed.

Assistant Chief David Dotson, the department's second in command that night, was driving home as Gates was headed for Brentwood. The two have long feuded, and Dotson said he left Parker Center because Gates had frozen him out of all operational authority. Last Wednesday, Gates demoted Dotson to deputy chief, supposedly for lying during an internal investigation five years ago. Dotson said it was because he criticized Gates's handling of the riots.

Gates also had kept Bernard Parks and Glenn Levant, two deputy chiefs then on duty, out of decision-making, supposedly because they cooperated with the Christopher commission. William Booth, a deputy chief close to Gates, was on vacation. Deputy Chief Ron Frankle, in charge of the Emergency Command Center when Gates left, said he did not know that Vernon had already planned an immediate tactical alert in event of a riot.

In addition, the LAPD was short-handed in the field because 12 captains were attending a training center at a seaside hotel in Ventura about 60 miles away. They were ordered back after violence began.

A key figure in the dispute about police response is Deputy Chief Matthew V. Hunt, who commands officers in South Los Angeles, which includes the 77th Street Division. Street officers pulled back from Florence and Normandie said they have high regard for Hunt, who was attending the rally at the First AME Church.

Hunt told the Los Angeles Times Thursday that, before the verdicts, he had pressed Gates for greater preparedness but was rebuffed. When violence erupted, he said, officers in the field were ill-prepared and quickly overwhelmed.

"I was going out of my mind," Hunt was quoted as saying. "We were just not prepared to deal with something with this magnitude in a very, very short time." Hunt also said conditions at a command post near the heart of the rioting were a "nightmare" in which telephones could not be hooked up and an "archaic" command post truck arrived without a computer.

Still, it is not clear why officers massed at 54th and Arlington were held back. Officer Kevin Robinson, who said he issued the first "help call" from Florence and Normandie, said reinforcements were not available from 77th Street Division, 1.8 miles away, because rioting spread so quickly.

"We had other situations going on," said Robinson, who blamed the verdicts for the violence. "If we had stopped it on that corner, we wouldn't have stopped the riots."

However, an officer in the group withdrawn by Moulin said a massive show of force at Florence and Normandie would have sent a "powerful message to the bad guys that we weren't going to let them take control." This view is held by several other officers who have experience in the south-central area but were not put on riot duty until the next day and said they do not understand the delays.

"We could have crushed it with a show of force," said Sgt. John Gambill, a motorcycle officer with long experience in the riot-torn area. "We're frustrated by being held back."

Critics outside the department share these views from line officers. "A quick and surgical response by arrest teams can save innocent lives, save the neighborhoods and take the most violent people off the street," said Joseph McNamara, former San Jose police chief and a veteran of street disturbances in Harlem and Kansas City. "By the time five or six hours have passed, you've lost it. The LAPD suffered the worst disgrace a police department can suffer, which is to lose a city through its own impotence. I blame Gates, who was horsing around." 'We Had to Move in Quickly'

Clyde Kronkhite, associate director of the Center for the Administration of Justice at the University of Southern California and a former high-ranking LAPD officer, said that, after the 1965 Watts riots, "we spent years dissecting what went wrong and decided we had to move in quickly should a similar situation develop. . . . There are always some people who are going to move in if the lid is off."

After studying the seven-day Watts rioting, in which 34 people died, the LAPD purchased armored personnel carriers equipped with battering rams as an alternative to sending small groups of officers into battle in vulnerable patrol cruisers. The carriers proved their worth later on the night of April 29 when police killed three gunmen in an exchange of gunfire without suffering losses. But the carriers were not deployed in the crucial early hours.

Because the LAPD did not follow its own precept at Florence and Normandie, luckless civilians driving through the area at the wrong time were left to the passions of the mob.

At 6:40 p.m., while Gates was on his way to the fund-raiser, Reginald O. Denny, a white truck driver, pulled his 18-wheel sand-and-gravel truck into the intersection. Five rioters surrounded him, and he was pulled from the truck and beaten savagely while millions of Southern Californians watched on live television. His life was saved not by police but by four good Samaritans from the crowd who helped him to a nearby hospital.

Last Friday, reviewing that incident, Gates said, "We regret the fact that we did not go in and do what we should have done and rescue Mr. Denny." But on April 29, at the fund-raiser, Gates said police had pulled back to redeploy and added, "There are going to be situations where people are going to go without assistance. That's just the facts of life."

More than any single event, the attack on Denny came to symbolize the horror of the riot for television viewers worldwide. Even police officers agree that it signaled that the LAPD no longer was in control and that it encouraged the killing, arson, looting and violence that followed.

Thousands of people, including off-duty police officers, called emergency 911 numbers and radio and television stations to ask why police were not aiding Denny. Many were sharply critical of the LAPD, which has long enjoyed strong public backing in Southern California outside minority communities.

Voicing the anger, conservative state Supreme Court Justice Armand Arabian, who usually avoids public controversy, warned Thursday that the LAPD is losing public support. "Where was the protection and service?" he asked in a speech to a Pasadena civic group honoring law enforcement officers. "Any slower response and we would have seen photos of policemen pasted on milk containers and listed as missing."

Public disgust with Gates and the LAPD has shaken his officers. "What's happened has made me ashamed to say what it is I do for a living," Gambill said.

Sgt. Dennis Zine called radio station KFI to defend the LAPD and Gates and denounce politicians who criticized them. "I apologize to the businessmen in south-central and Koreatown that we lost the war," he said tearfully. "I apologize to you. Your tax dollars were there, and we tried, we tried diligently and vigilantly. . . . "

One officer withdrawn in the original retreat from Florence and Normandie wept as he tried to explain what had happened. "We weren't allowed to do our job," he said. "We had the forces, and they weren't sent in. It's demoralizing to cops to be depicted as cowards, when our leaders wouldn't send us in."Special correspondent Leef Smith contributed to this report.