KIRKUK, Iraq (AP) – A suicide truck bomber targeted a police station in the oil-rich northern city of Kirkuk on Monday, killing at least 13 people and wounding dozens, including many children from a nearby school, police said.

The attacker rammed the truck into the concrete blast barriers protecting the back of the compound at about 11:30 a.m., detonating his explosives, which were hidden under a load of flour, local police spokesman Brig. Gen. Sarhat Qadir said.

The Rahim Awa police compound is in a predominantly Kurdish neighborhood in a northern part of the city, and other officials said American troops had been visiting an Iraqi criminal investigations unit when the blast occurred.

AP Television News footage showed one American soldier seen standing nearby with a bandage around his head and blood on the front of his uniform. The U.S. command in Baghdad said it was looking into the report.

He said 13 people were killed and 137 wounded. He also said at least 20 children on their way home from a nearby school were among the casualties, although he could not provide a breakdown of how many were killed or injured. The force of the blast also devastated four buildings in the area.

Doctors at the hospital worked in a scene of bloody pandemonium as wounded were brought to the emergency room. There was barely room to move.

Most of those being treated appeared to be either very young children or schoolgirls, many crying and with blood spattered on their clothes. Several badly mutilated dead bodies filled the back of a police pickup truck as an American helicopter flew overhead.

The attack comes days after the Iraqi government endorsed plans to relocate thousands of Arabs who were moved to Kirkuk as part of Saddam Hussein’s campaign to force ethnic Kurds out of the city in an effort to undo one of the former dictator’s most enduring and hated policies.

Kurds are seeking to incorporate the city, 180 miles north of Baghdad, and into their nearby autonomous region. But the move has met strong opposition from Sunni Arabs who fear being isolated from Iraq’s oil riches, which are concentrated in the north and the mainly Shiite south.

Many have blamed a recent rise of violence in Kirkuk on Sunni insurgents who fled Baghdad ahead of an American-Iraqi security crackdown in the capital.

The ancient city of Kirkuk has a large minority of ethnic Turks as well as Christians, Shiite and Sunni Arabs, Armenians and Assyrians. The city is just south of the Kurdish autonomous zone stretching across three provinces of northeastern Iraq.

Iraq’s constitution sets an end-of-the-year deadline for a referendum on Kirkuk’s status. Since Saddam’s fall four years ago, thousands of Kurds who once lived in the city have resettled there. It is now believed Kurds are a majority of the population and that a referendum on attaching Kirkuk to the Kurdish autonomous zone would pass easily.