A vehicle exploded Saturday behind a U.S. military police patrol in the tense central city of Samarra (search), wounding at least one Iraqi polieman but causing no U.S. casualties, a military policeman said.

Hospital officials in Samarra said two Iraqis were killed and 10 wounded, but initial reports were sketchy.

The American patrol was turning into a police station to link up with Iraqi police when a vehicle behind them exploded about 10:25 a.m., said Sgt. Maj. Nathan Wilson of the 720th Military Police Battalion (search).

U.S. officials said they did not know if the vehicle was moving or stationary when the blast occurred.

Iraqi police stations have been the target of frequent vehicle bombings in the past few months. Most stations are far less protected than American installations.

Samarra was the scene of heavy fighting on Nov. 30 when insurgents fought running battles with American troops in Samarra. U.S. officials estimated 54 Iraqis were killed. Five Americans were wounded.

The fighting erupted when attackers, many wearing uniforms of Saddam Hussein's Fedayeen (search) militia, opened fire simultaneously on two U.S. supply convoys delivering new currency to local banks.