BAGHDAD, Iraq - Insurgents attacked a police station Saturday in a Sunni Muslim neighborhood in Baghdad where U.S. and Iraqi troops raided a major mosque the day before in a crackdown on Sunni militants. Iraqi officials were trying to identify four decapitated bodies found in Mosul.

American and Iraqi forces detained 30 suspected guerrillas overnight in Mosul, the U.S. military said Saturday.

In western Baghdad, heavy fighting broke out between gunmen and Iraqi National Guards and American troops. Three Iraqi National Guardsmen were killed by roadside bombs in the same area, police said.

In the nearby Khadra area, two U.S. troops on patrol were injured when a roadside bomb exploded near their convoy, said policeman Ali Hussein of the Khadra police station. The U.S. military had no immediate confirmation of the incident.

Insurgents also attacked a police station in northwestern Baghdad with rocket-propelled grenades and small arms fire, witnesses said. On Friday, Iraqi and U.S. forces raided the nearby Abu Hanifa mosque - one of the country's most important Sunni mosques - in an operation that appeared to be part of a crackdown on militant clerics opposed to the U.S.-led attack on Fallujah.

U.S. troops discovered four decapitated bodies during military operations to purge insurgents from the northern city of Mosul, the military said Saturday.

The four decapitated bodies, whose identities have not been established, were found Thursday and have been turned over to Iraqi authorities, said Lt. Col. Paul Hastings, a spokesman for Task Force Olympia.

Three of the bodies were found by the road in a northeastern neighborhood of Mosul; the fourth was discovered in city's southwestern section, he said.

On Friday, a statement posted on an Islamist Web site in the name of Jordanian terror leader Abu Musab al-Zarqawi's group said it had "slaughtered" two Iraqi National Guard officers "in the presence of a big crowd" in Mosul. The claim included no photos or video and could not be verified.

There was no way of saying whether the bodies had been decapitated in a public manner, as the Web site claimed, said Hastings, adding that U.S. troops were "not able to identify them and say whether they were bodies of Iraqi National Guard, police or just anybody."

During raids on Friday, Iraqi commandos and U.S. forces detained 30 suspected militants, the military said. The men are in custody and undergoing interrogations.

In central Mosul, Iraq's third-largest city with more than a million residents, Iraqi commandos from the Interior Ministry arrested 23 people suspected of planning and conducting attacks against American and Iraqi troops.

U.S. soldiers detained four people after they tossed hand grenades and weapons out of a car as it approached a checkpoint. In western Mosul, U.S. troops detained three suspected members of a terrorist cell.

Back in Baghdad, clashes broke out around dawn in the Azamiyah neighborhood, and three U.S. armored vehicles were seen in flames, witnesses said. The U.S. military had no immediate comment on the incidents.

Footage by Associated Press Television News showed a smashed and burning U.S. Humvee with what appeared to be the remains of a body in the driver's seat.