Nearly simultaneous suicide bombings at three military checkpoints around a town in northern Iraq killed at least 15 persons Tuesday, while a bomb in the capital wounded dozens, police and hospital officials said.

More than 800 people have died in attacks across Iraq since April 28, when the country's new government was formally installed.

In the restive northern town of Tall Afar, meanwhile, U.S. and Iraqi troops launched an offensive against insurgents two days after regional officials announced an accord aimed at defusing tensions there.

Suicide car bombers struck three checkpoints manned by Iraqi soldiers outside the town of Hawijah, about 130 miles north of Baghdad. The attacks occurred minutes apart at about 9:30 in the morning local time.

The deadliest of the three, two miles west of Hawijah in Dibis, killed 11 persons, including five soldiers.

Details about the joint military operation in Tall Afar were not immediately available, but a U.S. military spokesman confirmed that an assault was underway there.

On Sunday, local officials and religious and tribal leaders from Tall Afar held talks that yielded a four-point agreement aimed at curbing insurgent and sectarian violence but acknowledging that failure to achieve peace would make a large-scale military incursion unavoidable.

Also Tuesday, the U.S. military announced the deaths of two Marines and a soldier in separate incidents.

One Marine died Monday from wounds sustained when a roadside bomb detonated near his vehicle on Sunday near the city of Fallujah. Another Marine died in Fallujah Monday in an attack the same day.

Both were members of Regimental Combat Team 8, 2nd Marine Division.

The soldier, according to the military, died of non-combat related injuries at a military camp near Baghdad International Airport. The soldier's unit was not identified and no further information was provided.

Barbash reported from Washington. Ani reported from Hawijah. Special correspondent Omar Fekeiki in Baghdad contributed to this report.