Three suicide car bombs exploded Thursday evening in crowded public places in the northern town of Balad, killing 63 people, according to police and local health officials.

In the western town of Ramadi, meanwhile, a roadside bomb killed five U.S. Army soldiers assigned to a Marine unit, the military said Thursday in a statement. It was the deadliest single attack on American troops in several months. The soldiers were conducting combat operations on Wednesday when the bomb went off, the military said.

The three explosions in Balad, which appeared to have been coordinated, all occurred within the space of an hour, police said. At 6:50 p.m., just as the light faded from pink to black, the first bomb exploded in a crowded vegetable market. Twenty-five minutes later, another bomber struck at the Moat Gate near a Shiite mosque where a meeting was taking place. About a half-hour later, a car bomb detonated on Bank Street.

Qasim Hazim Qaisi, a physician at the main hospital in Balad, said 63 people were confirmed dead. "We found 40 intact bodies, but we have many legs and hands and arms," Qaisi said. He said 85 people were wounded.

Late Thursday night, al-Arabiya television reported that 85 people had been killed. The Associated Press and the Reuters news agency, quoting health officials, put the toll at more than 60 dead.

Although it was not immediately clear who had carried out the attacks, Balad is populated mostly by Shiites but is situated inside Iraq's Sunni Triangle, about 50 miles north of Baghdad. Recent violence in Iraq has taken on an increasingly sectarian cast, with the Sunni-dominated insurgency attacking Shiite civilians and targets associated with Iraq's Shiite-led government.

In Baghdad on Thursday, U.S. forces raided the homes of two Sunni political leaders, confiscating weapons and capturing four bodyguards whom the U.S. military labeled terrorists.

The early morning raids took place at the homes of Adnan Dulaimi, the secretary general of the People for Iraq Conference, and Hareth Obeidi, a leading member of the Iraqi Islamic Party. Both groups oppose a proposed constitution that will be put to a national vote on Oct. 15 but are considered relatively moderate compared with other Sunni organizations. Both parties officially boycotted the national election in January but did not stop their followers from voting, and both participated in the drafting of the constitution.

Dulaimi swiftly denounced the raids, calling them unprovoked. In a news conference, he charged that the raid "terrorized" his family and "further complicates the already complicated situation." All four guards arrested worked for Dulaimi.

Dulaimi said the American soldiers behaved "as if they were attacking a castle, not the home of a normal person who advises Iraq's interim government and has called for reconciliation and renounced sectarianism."

No arrests were made at the home of Obeidi, who is not as well-known as Dulaimi but who was a member of the committee that drafted the constitution.

A spokesman for the Iraqi Islamic Party said Obeidi was shocked by the raid on his home. "We don't know why they are harassing us in this way and what the purpose is behind all of this, particularly since we are involved in the political process and we are urging our constituency to take part in the referendum and the election," said Nasir Ani, a senior member of the party. "We feel very disturbed and surprised by such acts."

Most Sunni parties oppose the new constitution, which would create a federal government, dividing power between ethnic Kurds and Shiite and Sunni Arabs. The Sunnis, who make up an estimated 20 percent of Iraq's population, enjoyed broad power under deposed leader Saddam Hussein, and many said that federalism would give them too soft a voice in government.

The U.S. military said its soldiers met resistance at Dulaimi's home when they conducted the raid at about 2:10 a.m. local time. Maj. Flora Lee, a military spokeswoman, said some of the residents of the two-building compound "came out willingly, but others refused." Four of Dulaimi's guards were "identified for their alleged involvement in terrorist activities," she added.

The men were picked out by another detainee, she said, adding that the U.S. troops discovered 15 AK-47 assault rifles and body armor. Political leaders in Iraq are routinely targeted by insurgents, and nearly all of the major parties have their own security forces.

In Baghdad's Dora neighborhood, gunmen opened fire on a Shiite bakery, killing three civilians, the Associated Press reported, quoting police. In another incident, armed men shot at a minibus carrying government cleaners to work, killing two and wounding seven, police said. Two civilians and four police officers were killed in drive-by shootings elsewhere in the capital, and a 12-year-old living in a homeless shelter was killed by a mortar shell, according to the AP.

In the southern city of Najaf, the Shiite cleric Moqtada Sadr rejected recent violence and said members of his militia were not behind recent attacks on a rival political group. Six children were killed Wednesday night in a bomb attack on one of Sadr's guards.

Special correspondents Salih Saif Aldin in Tikrit and Saad Sarhan in Najaf contributed to this report.

Iraqi medics help a man injured in a blast in Najaf. Also in that city, the Shiite cleric Moqtada Sadr said his militiamen were not behind recent attacks on a rival group. Six children died this week in a bomb attack on one of Sadr's guards.