Three schoolboys were among at least 10 people killed in Iraq on Tuesday, extending a wave of bloody attacks that have rocked the country since American troops pulled out.

Several of the Tuesday attacks struck predominantly Sunni areas north of Baghdad, though an evening blast in the capital appeared to target Shiite pilgrims commemorating a holy period known as Arbaeen.

The violence followed deadly car bomb blasts the evening before, and pushed to more than 100 the number of Iraqis killed in less than a week.

Many of attacks in recent days have targeted Iraq's Shiite majority, raising fears of a serious outbreak of sectarian violence following the withdrawal of U.S. troops last month.

Large-scale sectarian fighting pushed the country to the brink of civil war in 2006-7. Well-armed Sunni insurgents and Shiite militias continue to operate in the country.

The increase in violence comes as Iraq's leaders remain locked in a political crisis that is stoking tensions between the Shiite majority now in power and the country's Sunnis, who benefited most from ousted dictator Saddam Hussein's rule.

Tuesday's youngest victims were the three boys, nine and 10 years old. They were hit by a roadside bomb on their way to school near Saddam's hometown of Tikrit, 80 miles north of Baghdad, police and hospital officials said.

Northwest of the capital, two agriculture ministry workers were killed and a third was wounded when a bomb stuck to their car exploded in Shurqat, about 155 miles northwest of Baghdad.

In the evening, gunmen ambushed an Iraqi army checkpoint in the former Al Qaeda stronghold of Mosul, killing two soldiers. Attackers elsewhere in the city shot and killed a policeman from a speeding car, officials said.

A roadside bomb in western Baghdad late Tuesday killed two Shiite pilgrims. They were walking to the city of Karbala, 50 miles south of the capital, for Arbaeen, which marks the end of 40 days of mourning following the anniversary of the death of Imam Hussein, a revered Shiite figure.

The officials spoke on condition of anonymity because they were not authorized to talk to reporters.

The leaders of Iraq's rival sects have been locked in a standoff since last month, when the Shiite-dominated government called for Sunni Vice President Tariq al-Hashemi's arrest on terrorism charges, just as the last American troops were completing their withdrawal from the country.

Al-Hashemi, Iraq's highest ranking Sunni politician, remains holed up in the semiautonomous Kurdish region in the north, out of reach of state security forces.

The prime minister of neighboring Turkey urged Iraq's leaders Tuesday to ease sectarian tensions. Recep Tayyip Erdogan said they would be held responsible for bloodshed in the event of a civil war.

Erdogan said Iraqi leaders who pave the way for a sectarian conflict would be "condemned to be remembered as the devil."