Clashes erupted Friday between two Iraqi army units following a roadside bombing north of the capital, and Iraqi police said a Shiite soldier was killed in an exchange of fire with a Kurdish unit.

The U.S. military and Iraqi police provided differing accounts of the incident, which began with a roadside bombing near Duluiyah, about 45 miles north of Baghdad.

The Americans said one soldier from the Iraqi army's 1st Battalion, 3rd Brigade, 4th Division was killed and 12 were wounded in the attack.

But Iraqi police 1st Lt. Ali Ibrahim said four were killed and three others wounded. He identified the soldiers as Kurdish but did not specify their unit.

According to both accounts, the wounded were rushed to the U.S. military hospital in Balad. Police said that when the Kurdish soldiers drove up to the hospital, they began firing weapons to clear the way, and one Iraqi Shiite civilian was killed.

When security rushed to the scene, the Kurds decided to take their wounded elsewhere, Iraqi police said. Iraqi troops from a separate Shiite unit tried to stop them and shots were fired, Iraqi police said.

The U.S. account said that an Iraqi soldier from the 3rd Battalion, 1st Brigade was killed in a "confrontation" as the other Iraqi troops were trying to remove their wounded. Iraqi police identified the dead soldier as a Shiite. But the U.S. statement did not say what prompted the soldiers to try to take wounded comrades away from a hospital — the best equipped American medical facility in the country.

A third Iraqi army unit set up a roadblock in the area and stopped the soldiers who were leaving with their wounded, the U.S. statement said. American troops intervened at the roadblock and calmed the situation.

The U.S. said the Iraqi army was investigating the incident.

Thousands of Kurdish peshmerga militiamen were integrated into the Iraqi army and provide security in areas with large Kurdish populations, some of which are located near Shiite and Sunni Arab communities.

The peshmerga also provides security in the three provinces that form the Kurds' self-governing entity in the north.