The bodies of six persons, two of them children, were found today in the smoldering ashes of a radical group's row house headquarters, leveled in a police assault Monday that ignited a fire and destroyed almost two blocks of a west Philadelphia neighborhood.

Authorities said the charred remains of two men, a woman and a female child, and parts of a fourth adult and another child were discovered in the rubble before police ended their search at 8 p.m. It is to resume at dawn.

Authorities said they do not know how many members of MOVE, a back-to-nature group, survived the daylong siege, which included an 80-minute gun battle and a six-hour wind-blown blaze that left about 300 persons homeless and caused an estimated $5 million in damages.

With city officials under mounting criticism, Mayor W. Wilson Goode said in a special television address:

"I think we did everything possible to negotiate and bring about a peaceful result. MOVE members, however, wanted and desired a violent confrontation."

Goode added that the group, whose members are thought to number only a few dozen, "turned a peaceful block into an armed camp" and could not be allowed to "hold an entire city hostage."

Visiting the once quiet, middle-class neighborhood this morning, Goode said he was "devastated by what I saw" and "saddened by the loss of property."

He told homeless residents, "We will rebuild these homes . . . as quickly as possible."

Today, in the 6200 block of Osage Avenue, where MOVE established its headquarters three years ago in the two-story row house, only smoldering foundations showed where many houses had been. Trees, yards and walls were gone. The homeless mourned their losses, some complaining that all of their possessions were destroyed.

City managing director Leo Brooks said 53 of 61 houses along two streets were destroyed or would have to be razed. Goode said it would cost about $70,000 apiece to build comparable houses.

Some of the disfigured bodies were found in the rear basement. Officials said they also found three 55-gallon drums containing a liquid not immediately identified, two large propane tanks, a generator and several half-inch steel plates bearing bullet marks, apparently from the lengthy shootout at dawn Monday.

At a news conference tonight involving ranking city officials, Police Commissioner Gregore Sambor referred to the house as "the most extensive fortification that I have ever seen in 35 years" as a policeman. He said the rooftop bunker and the house's interior included heavy timber and steel plating on reinforced supports. Also inside, he said, were "tree trunks with the bark still on them in which weapons ports were cut."

Authorities also said that one of two group members captured after the fire broke out told them that gasoline had been poured throughout the house Monday. Goode said tonight that some investigators suspect that the fire "may have been [one] started from the inside."

Goode said police had been told that tunnels were dug under adjoining houses and that MOVE was "prepared to blow up an entire block."

Initial reports from authorities Monday night indicated that five males and 10 children were thought to be living in the house and that three adult males may have escaped, perhaps through a tunnel, after the fire began. There were conflicting reports today about possible MOVE survivors.

The crisis escalated Monday morning when police went to the house to serve arrest warrants charging four MOVE members believed to be there with making terrorist threats, harassment, possession of explosives and conspiracy.

Someone inside the house mocked Sambor's verbal order to come outside and, a few minutes later, the gun battle began.

After hours of siege punctuated by periodic reports of shooting, the fire was ignited about 5:30 p.m., moments after a police helicopter passed over the house and an explosive device was dropped onto the roof.

Sambor said tonight that the device consisted of two one-pound tubes of a blasting material called Tovex, which he said is used primarily in mining and is "equivalent to dynamite and much safer to handle."

He said police hoped that it would burst the rooftop bunker and allow them to lob in more tear-gas canisters.

He said that police officials had made what he termed "extensive tests" of the device at undisclosed times and that "never during any of these tests" did fire occur. At the time the device was dropped, he said, police did not believe the rooftop bunker was occupied.

The blaze, described by officials as one of the city's worst residential fires, burned out of control until shortly before midnight.

Burton Caine, president of the Philadelphia chapter of the American Civil Liberties Union, said use of the device was "totally unjustified," adding that "trained public-safety officials should have known that the dropping of a bomb onto a row home -- full of ammunition and other explosives -- in a tightly compacted area . . . is like lighting a match in a room full of gas."

Officials said the bunker was not completely destroyed by the explosion, and Goode said tonight that Brooks decided to allow the rooftop to burn. Firefighters did not intervene for an hour, and fire spread to adjoining row houses in the densely constructed neighborhood.

The first of six fire alarms was not sounded until 6:55 p.m., about 20 minutes after two water cannons, which propel 2,000 gallons of water a minute and had been trained against the house earlier, were used on the blaze with little effect.

Fanned by brisk winds, the fire rapidly became an inferno, sending huge clouds of black smoke and glowing ash over a wide area of west Philadelphia and raging out of control. Teary-eyed homeowners stood at police barricades and watched their property burn.

Tempers rose as residents four and five blocks from the MOVE house attempted to sprinkle water on their rooftops.

"It's incredible, totally unbelievable that they would allow a neighborhood to be destroyed like this," resident Charles Griffin shouted. "This is a very primitive tactic for them [police and fire officials] to use."

Fire Commissioner William C. Richmond said today that, during the first few hours after the fire, his men were driven back four or five times by gunshots or reports of shooting. He said he ordered his men to take defensive positions and added, "We are firefighters, not infantrymen."

Police, who said they fired 7,000 to 10,000 rounds of ammunition into the house during the day, engaged in a shootout with three MOVE members at about 7:20 p.m. in an alley behind the house, authorities said. The fate of the three apparently had not been determined today.

Twenty minutes after the alley shootout, police said, they captured Ramona Africa, 30, and Bertie Africa, a 9-year-old boy. The youngster was hospitalized and reported in satisfactory condition with second-degree burns.

Ramona Africa, who refused hospital treatment for less serious burns, was arraigned today, shouting obscenities at Bail Commissioner Charles E. Murray. "You . . . tried to burn my kids and murder us all. You should be charging that Wilson Goode. You kidnaped me off the street," she screamed.

She was ordered held on $3 million bond on charges of assault, reckless endangerment of another person, possession of weapons, criminal conspiracy, resisting arrest, riot and risking catastrophe.

Goode said that, as mayor, responsibility for everything that happened was his. "We had a well-thought-out plan," he told reporters this afternoon. "That plan was to avoid loss of life. The one thing we didn't anticipate was when the percussion grenade went off it would cause a fire. That was an accident."

"I am saddened by what happened as much as anyone," he said. Later, he added, "If I had to make the same decision, I would do it again. I could not allow a revolutionary group to hold the city hostage."

City officials, businessmen and politicians voiced general support for Goode as a massive effort was launched to provide food, shelter and clothing for the homeless.

Groups representing lawyers and certified public accountants pledged to provide free legal and bookkeeping help. Dozens of groups, led by the Red Cross and Salvation Army, mounted efforts to collect food, clothing and money.

Nonetheless, the devastation left a deep sense of unease. City Council member Joan Specter called on Goode to appoint a panel to investigate the incident, and the mayor said he liked the idea.

"I don't have any opinions. I only have questions," said Specter, wife of Sen. Arlen Specter (R-Pa.). "We are all in shock that a bomb was dropped."