They saw the vehicle first, a blue Malibu, rounding the circle with the golden statue of the Iraqi poet Marouf Rasafi standing majestically in the center. The car sped up as it headed toward Martyr's Bridge, where Iraqi police had set up a roadblock.

The police and civilian witnesses saw the driver as he roared by -- his neatly trimmed beard, sunken cheeks, slicked-back blond hair. The man looked straight ahead, his hands on the wheel. As he got closer to the roadblock, he bowed his head, ducking below the dashboard, and the car blew up in a burst of flame and flying metal.

The suicide car bombing, which killed five people and wounded 20, according to an Iraqi Health Ministry official, was one of two that exploded in Baghdad on Friday morning. The other killed only the driver and a passenger, officials said.

At the same time, Iraqi security forces backed by U.S. soldiers in Humvees and Bradley Fighting Vehicles raided residences along Haifa Street, the scene of a deadly bombing on Tuesday that killed at least 47 people and wounded 114.

And in the city of Fallujah, 35 miles west of the capital, U.S. warplanes launched two strikes against targets associated with the insurgent leader Abu Musab Zarqawi.

The first strike came early Friday morning and targeted a compound in south-central Fallujah harboring individuals "believed to be associated with recent bombing attacks and other terrorist activities throughout Iraq that have resulted in the deaths of numerous Iraqi citizens," the military said in a statement.

Health officials in Fallujah and Baghdad said the strike also killed women and children. Saad Amili, a Health Ministry spokesman, said 44 people were killed and 27 wounded. The wounded included 17 children, two women and two elderly men, he said. The director of Fallujah's hospital, Rafa Hayad Issawi, said the death toll was 51 and included 10 children and 11 women.

A Fallujah resident who lives near the site of the airstrike said insurgents had been congregating in the area early in the night but had dispersed before the attack.

The second strike occurred on Friday evening and targeted a meeting of 10 Zarqawi associates near a school and a mosque. In a statement issued after the attack, the U.S. military command in Baghdad said that "there was no indication that any innocent civilians were in the immediate vicinity of the meeting location." The military also said its initial reports indicated that the strike caused no damage to either the mosque or the school.

The assaults came on the heels of a major airstrike Thursday night in which the U.S. military targeted a compound south of Fallujah where it said an estimated 90 foreign fighters had been gathering. The military estimated that 60 non-Iraqis were killed in the attack, although there was no independent confirmation of the death toll. The Associated Press reported that residents of a nearby village were observed digging communal graves Friday to bury the dead in groups of four.

On Haifa Street, a notorious Baghdad hangout for criminal gangs and foreign guerrillas where a U.S. military helicopter fired into a crowd on Sunday and killed 13 people, residents said they were awakened at about 4 a.m. Friday by a voice from a loudspeaker. It instructed them to remain indoors and not turn on their lights and called on insurgents to turn themselves in to local police stations "to avoid clashes that kill more innocent people."

Witnesses said they could hear shooting and grenade explosions outside as dawn broke along the street, a major north-south artery on the west bank of the Tigris River. Witnesses said they could see members of the Iraqi National Guard raiding houses and pulling out people. A group of about 20 to 25 was rounded up and placed in the middle of the street, as Guardsmen piled confiscated weapons and rocket-propelled grenades alongside.

Led by a gunner in a pickup truck who had the Iraqi flag draped around his shoulders and followed by U.S. armored vehicles, a procession of Iraqi army and National Guard vehicles rolled down the street, returning any fire from insurgents. One person was killed and nine wounded, including a Guardsman, officials said. Sabah Kadim, a spokesman for the Iraqi Interior Ministry, said 63 people were arrested, including Sudanese, Egyptian and Syrian fighters.

"The people we arrested are members in organized gangs and terrorists," the spokesman said. "Those are the ones responsible for the lack of security in Iraq now."

As the raid began, a vehicle attempted to break through a checkpoint set up to enforce a curfew on the neighborhood. When police fired at the car before it reached the checkpoint, it exploded, killing two people inside, U.S. military and Iraqi authorities said.

At the scene of the car bomb near Martyr's Bridge, which went off at about 12:15 p.m., witnesses described devastating carnage and burning wreckage.

Salah Ahmed, 54, a truck driver, was attempting to cross Martyr's Bridge to Haifa Street when he was stopped by Iraqi police. Eight police vehicles blocked access to the bridge, and police with guns were milling about, he said.

Ahmed said he had climbed out of his vehicle and perched on a wooden cart, waiting to be allowed across the bridge, when he saw three cars get turned away by the police. A fourth car, the Malibu, circled the Rasafi statue and kept going until it exploded, he said.

"I saw his face," Ahmed said, his knee bleeding from a shrapnel wound. "They didn't shoot at him. When the explosion happened, we were scared. We ran away to take cover."

About an hour after the blast, Ammar Ali, an Iraqi police officer, was still walking around in shock, his blue uniform shirt soaked with the blood of a colleague.

"We were protecting the Americans so nobody could get close to them," Ahmed said, his face stiff as he spoke. "But we were not as careful as the Americans. We should be more careful. We didn't think this would happen."

Another police officer, who gave his name as Hayder, stood nearby, angry and fighting back tears. "We ask the Iraqis to help us so we will be able to control the situation, get rid of the terrorists and live in peace," he said. "All the people who were killed were Iraqis."

Asked if he would quit, Hayder shook his head. "No, we know how dangerous this job is," he said. "These bombings will make us work hard to get rid of the terrorists."

Correspondent Rajiv Chandrasekaran and special correspondents Bassam Sebti, Luma Mousawi, Naseer Nouri and Omar Fekeiki contributed to this report.

A wounded Iraqi policeman is rushed to a hospital following the explosion of a car bomb in central Baghdad.