KABUL, Afghanistan — An Afghan policeman opened fire on U.S. troops inside a police station in eastern Afghanistan, killing an American soldier and wounding several other people, officials said today.

The shooting took place in Paktia province on Sunday after American troops and Afghan police brought militant suspects to the station. An officer already at the station then opened fire, a NATO official said on condition of anonymity because the information was not supposed to be released publicly.

Paktia provincial police chief Gen. Esmatullah Alizai confirmed that a policeman shot an American. "Yes, this incident happened," he said before abruptly hanging up the phone.

A statement from NATO's International Security Assistance Force issued today said that an "altercation" took place in the station. But the statement did not include any details about the shooting.

The Americans and Afghans were on a joint patrol when they were attacked by a roadside bomb Sunday. No one was injured.

Militants observing the attack then shot gunfire at the Americans and Afghans before fleeing. After military fighter aircraft tracked down the militants, the soldiers apprehended them and tested them for explosives residue, the NATO official said. The suspects tested positive.

Seven detainees were then taken to the Afghan police station in the Jaji district center of Paktia, where the Afghan policeman opened fire.

The police officer wounded three or four American soldiers, an Afghan interpreter for the military and one of the detainees, the NATO official said.

It wasn't clear if the Afghan policeman was a militant who had infiltrated the force, the NATO official said, though it was a possibility.

"It's not indicative of the whole police force," the NATO official said. "It's one crazy guy. It doesn't change our partnership or commitment."