Heavy fighting engulfed downtown Baqubah on Saturday as U.S. troops and black-clad insurgents clashed intermittently in palm groves, traffic circles and major avenues only days before a fledgling Iraqi government is scheduled to assume political authority after 15 months of occupation.

Following the coordinated attacks that ripped through six cities on Thursday and killed more than 100 Iraqis, U.S. military commanders said they expected more strikes as insurgents tried to disrupt the transfer of power on Wednesday. Those predictions proved true before 8 a.m. when insurgents operating in small groups peppered government buildings with rocket-propelled grenades and rifle fire.

Many of the insurgents then dissolved into narrow alleys and clusters of date palms, a pattern that occurred throughout the hot, windy day.

U.S. troops pursued them in armored convoys and on foot through a downtown district crowded periodically with bewildered civilians, some of whom later joined the fight on the side of U.S. troops. On the city outskirts, meanwhile, U.S. soldiers raided houses looking for guerrillas and weapons stockpiles.

At times, the attacks followed amplified calls from Baqubah's many minarets, although soldiers were unsure if the messages were coordinating insurgent operations, as had been the case in previous uprisings.

By day's end, the outcome of the fighting remained inconclusive. U.S. officials later said six guerrillas were killed in the fighting. But to the soldiers watching the battlefield from a rooftop near the heart of the fighting, the challenges of imposing order here had become dauntingly clear after a day of clashes complicated by shifting rules of engagement, sapping heat and unorthodox guerrilla tactics.

"It's ever-changing scenery," said Sgt. Tom Evans, 34, a squad leader from 3rd Platoon, Bravo Battery, of the 1st Infantry Division's 3rd Brigade Combat Team. Reflecting on the days remaining before the transfer of sovereignty, he said: "The closer we get to 30 June, the more of this stuff is happening."

The streets of this farming center 35 miles northeast of Baghdad had filled with traffic Saturday morning when insurgents blasted the Iraqi police station across the street from a compound used by the U.S.-led Coalition Provisional Authority. Rocket-propelled grenades slammed into several buildings, sending showers of debris into the streets below.

The firing came from both ends of the street below Evans's men, who manned machine guns and Mark-19 grenade launchers from sandbagged positions overlooking the occupation compound's north side. A few blocks farther north, the violet dome of the Anafsa mosque and its turquoise-tipped minaret peeked over three-story apartment buildings.

In the hours that followed, fighting swirled around the soldiers' tumbledown building, centering on the provincial government facility known as the "Blue Dome." That building, two blocks from the compound, sits near a palm grove in Baqubah's civic center.

In recent days, the insurgents have attacked the area repeatedly in an apparent effort to cut it off from additional U.S. forces and effect a symbolic capture of the city's seat of political power. Military commanders predict that the insurgents' objective will not change but that the scale of their attacks will grow more ambitious.

"Watch them, watch them!" shouted Evans, an ebullient Texan with a well-trimmed mustache and little patience for his soldiers' frequent swearing over the radio network. "Three individuals on your right."

A blue four-door sedan pulled into the empty avenue before 9 a.m. and appeared to fire a grenade into a building about 100 yards from the compound. Evans's soldiers fired on the car, and the men inside darted down a side alley.

Through sniper scopes, the soldiers could see the men partially hidden behind a blue banner with Arabic inscriptions. An informant later told a guard at the compound gate that the car contained weapons.

A crowd of about 40 men gathered on the corner near the thickening traffic on Orange Circle, just beyond the immobilized car. Every few minutes, one or two rifle shots sounded.

"Drink water, guys, drink water!" Evans yelled, as the heat, which would push above 115 degrees in the next few hours, took hold. "Looks like it's going to be a long day."

From a rooftop one floor below, Sgt. Brett Granrose, 25, from Stillwater, Okla., stared through the scope of his M-4 rifle and saw increasing activity around the car, which sat 250 yards away with two of its doors open. Backed-up traffic began to eddy around it, frustrating Evans and emboldening one of the men behind the banner. Slowly, the man moved toward the car.

"If he touches that car, shoot it," Evans yelled to Granrose. A minute later, Granrose squeezed the trigger, and a shot cracked down the avenue. The man fled.

Soon afterward, the strains of the muezzin's call rang out from the minaret loudspeakers. Evans checked his watch. It was 10 a.m.

"The prayer guy is starting early today," he said. He keyed his radio, calling for an interpreter to come up to the roof and translate the message. Before one arrived, the crackle of small-arms fire sounded from less than a block away.

"We have gunshots, south gate," Evans said into the radio. Then, to no one in particular, "They just picked it up for some reason."

Just as quickly, the popcorn pop of small-arms fire gave way to long, thudding bursts from heavy machine guns. Grenade explosions thumped in long staccato strings.

"Be advised the Blue Dome is getting rocked," Evans announced into the radio. "Seems like the action is moving in our direction, so be ready. We're looking northwest, moving our direction."

Suddenly, the world below was in motion. Crowds ran down the avenue past Orange Circle, empty of the traffic that had clogged it minutes before. Only the muezzin and gunfire interrupted the hush that had fallen over the city of 250,000 people.

"Light it up, baby!" Evans shouted above the din. His men cheered as a column of Bradley Fighting Vehicles rumbled past toward the palm grove. The small-arms fire moved to within 50 yards of the occupation complex, directed at the police station.

At the start of the day's fighting, Col. Dana Pittard, the brigade commander, had met with the city's police chiefs, who pleaded for heavier weapons to repel the attack.

"We're going to arm them," said Pittard, who would provide machine guns and rocket-propelled grenade launchers. "They want to fight, which is something we did not see in April" when the police fled in the face of a similar uprising.

Pittard also said he received reports that Iraqi civilians, carrying AK-47s permitted under occupation regulations for protection of homes, had begun pursuing the insurgents on their own. According to one report, a group of them ran into the palm grove, a favorite insurgent staging area, amid heavy firing on the Blue Dome.

"We've never seen that before," Pittard said. "I'm very encouraged by it."

The civilians' involvement necessitated new rules of engagement for Evans's men. Soldiers had been permitted to fire on anyone carrying a weapon or dressed in the insurgents' signature black uniform. But Evans informed the men that for the rest of the day they could fire only on people who were both armed and clad in black.

As heavy fighting ebbed and flowed over the next hour, the blue sedan remained; in the words of one soldier, it was "a Mexican standoff." At 11:30 a.m., a man in gray slacks and a gray striped shirt appeared at the guard post and offered to retrieve the weapons from the car. Evans agreed, with one caveat.

"If he turns off the street, shoot him," he told his rooftop snipers. He also ordered a squad from the Iraqi Civil Defense Corps, a U.S.-trained paramilitary force whose woefully under-equipped recruits have generally performed poorly against a more skilled insurgency, to escort the volunteer.

From a side street, the man in gray appeared, flanked by five civil defense soldiers. The men gingerly made their way along the empty street toward the car, watched by a gathering crowd. The Iraqi soldiers, only one of them in body armor, fired into the air.

The group covered the 250 yards in a minute, and just as quickly the civilian ran back to the compound with news. The weapons, he said, consisted of several rocket-propelled grenades wrapped in wires -- an apparent booby trap.

But the civil defense soldiers continued to check the car, removing four grenades, a launcher and an ammunition vest. They tested the trunk before one of them noticed wires leading to it from the back seat. Slowly, they headed back to the compound with their find.

"Good job, guys!" Evans yelled.

A half-hour later, a U.S. infantryman knelt in the avenue 100 yards from the car, holding on his shoulder an AT-4 rocket launcher. He took aim at the blue sedan as soldiers gathered on the roof to watch. The private squeezed the trigger, and with a deafening boom the car exploded to hoots and cheers.

"You just gave the guy one less reason to wash it," one soldier yelled.

The car burned for hours. Then a group of Iraqis, some of them children carrying white bags, stripped the charred mess.

The day wore on, the fighting flaring and fading in a cycle that kept the soldiers on edge. At twilight, Evans headed for his bunk and a few hours' sleep. The muezzin's call echoed in the near distance.

"You wouldn't believe this place just after the sun rises," Evans said. "It's beautiful."

1st Infantry Division troops search for weapons in Baqubah, where insurgents mounted hit-and-run attacks throughout the day.Sgt. 1st Class Cameron Gaines oversees the search of a car in the farming center of Baqubah, where six insurgents were reported killed.Acting on an informant's tip, soldiers raid houses outside the city. Some civilians joined the fighting on the U.S. side.