KARBALA, Iraq — Suicide bombers targeted Shiite pilgrims in the south and police recruits in central Iraq today, killing about 100 people in the deadliest string of attacks in the country since September.

The U.S. military said a roadside bomb killed five American soldiers patrolling in the Baghdad area. Earlier, Iraqi police Capt. Rahim Slaho said the U.S. convoy was heading for the Shiite holy city of Karbala when it was attacked 15 miles south of the city, and five soldiers were killed.

Today's bombings came a day after insurgents killed 53 people, including 32 killed by a suicide attacker at a Shiite funeral east of Baqouba.

The blast near the Imam Hussein shrine in central Karbala, 50 miles south of Baghdad, killed 49 people and injured 52, said Karbala police Col. Razaq al-Taie.

The site was a scene of chaos with men ferrying the wounded in push carts and pools of blood on the ground. The bomber appeared to have set off the explosion only about 30 yards from the shrine in a busy shopping area.

In Ramadi, police and hospital officials said at least 30 people were killed and 40 injured in a suicide attack on a line of police recruits.

The attack took place at a police screening center in Ramadi, an insurgent stronghold 70 miles west of Baghdad. At least 30 people were killed, said Mohammed al-Ani, a doctor at Ramadi General Hospital and police Capt. Nassir al-Alousi.

The U.S. military did not have a casualty figure, but said that a suicide bomb exploded at 10:55 a.m. near the Ramadi Glass and Ceramics Works "where screening for Iraqi police officers was taking place."

The Karbala bomber detonated a vest with about 17 pounds of explosives and several hand grenades, al-Taie said. Small steel balls that had been packed into the vest were found at the site, as was one unexploded grenade, he said.

Many pilgrims travel to Karbala on Thursdays to be at the holy site for Friday prayers. One pilgrim, Mohammed Saheb, said he travels to Karbala every Thursday.

"I never thought that such a crime could happen near this holy site," said Saheb, who sustained a head injury. "The terrorists spare no place from their ugly deeds. This is a criminal act against faithful pilgrims. The terrorists are targeting the Shiites."

Karbala's governor, Aqeel al-Khazraji, blamed "takfiris and Saddamists" for the Karbala attack. The takfiri ideology is followed by extremist Sunni Muslims bent on killing anyone considered to be an infidel, even fellow Muslims who disagree with their doctrine. Al-Qaida in Iraq leader Abu Musab al-Zarqawi is a takfiri.