Two suicide attacks and two assassinations on Thursday killed at least 17 people in the Iraqi capital, whose already bloodied populace is preparing for a historic vote on a new constitution in nine days.

An American soldier was also killed when his patrol struck a roadside bomb in north Baghdad at 8:15 a.m., the military said.

As U.S. and Iraqi officials had predicted, violence has surged in parts of the country in advance of the Oct. 15 referendum on a contested constitution that would set the framework for a new government.

In the deadliest attack Thursday, a suicide bomber with explosives strapped to his body blew himself up inside a minibus carrying civilians and police academy students on Palestine Street in northeast Baghdad.

Ten people, including the students, were killed and seven were wounded, according to Iraqi police Lt. Sadiq Ali Lafta, who spoke at the scene.

The attack occurred at an intersection near the police academy and the Oil Ministry. Ambulances and fire trucks rushed to the scene, while police vehicles surrounded the burning minibus.

Two women were killed when a suicide car-bomber struck in the morning in Baghdad, apparently aiming for a passing convoy of foreign contractors, witnesses said. And unknown gunmen shot and killed Judge Munqith Faroun and two of his bodyguards in the Ameriya neighborhood of western Baghdad, according to officials at the Interior Ministry. Faroun was on his way to work at the Central Criminal Court of Iraq when he was attacked around 8 a.m. He had presided over cases involving suspected insurgents and recently handed down death sentences.

Northwest of Baghdad, gunmen shot and killed Nayef Abdul Qadir, the principal of Noor High School in a predominantly Shiite neighborhood, the officials said.

Just south of Kirkuk, in northern Iraq, five members of the Oil Ministry special police were killed and four were wounded when a roadside bomb exploded near their convoy in Othaim, said Gen. Sarhad Qadir of the Kirkuk police. Qadir said ensuing clashes between armed men and the police lasted for four hours.

Meanwhile, a military operation continued in western Iraq, where U.S. troops and Iraqi security forces tried to stabilize the region in advance of the referendum.

About 350 U.S and Iraqi troops, down from nearly 3,000 at the start of the operation two days ago, searched for fighters and weapons in the Euphrates River towns of Haditha, Haqlaniyah and Barwana.

Early Thursday, U.S. Marines detained a man in Barwana for possession of a mortar system, the military said in a statement. At noon in Haditha, Marines and Iraqi security forces discovered and destroyed a roadside bomb made from two 155mm artillery rounds. Two similar devices were found the day before.

Six men suspected of having links to al Qaeda have been killed in the fighting and about 110 have been detained, the U.S. military said.

A U.S. soldier examines a minibus blown up by a suicide bomber in a Baghdad attack that killed 10 people, including police academy students. An Iraqi man comforts his son after the boy was wounded during the minibus bombing.