Afghan officials say a suicide bomb attack has killed at least four people and wounded 10 others in northern Afghanistan.

Officials say a suicide bomber detonated a car bomb just before dawn Tuesday outside a compound that houses two separate private security companies in the city of Kunduz.

Police say two other militants then stormed the facility, resulting in a two-hour-long firefight with police. The fighting ended when the two militants inside one of the buildings detonated their explosives.

Four private Afghan security guards were killed. An Afghan policeman was among those wounded.

The Taliban has claimed responsibility for the attack.

Separately, Afghan officials said Monday a NATO airstrike killed four Afghan police officers and wounded two others in the country's east.

The governor of Nuristan province, Jamaluddin Badar, said coalition forces also detained 12 police officers after NATO aircraft bombed the police post in the Wama district late Sunday.

Badar said the strike was based on wrong intelligence. He said the officers were wearing police uniforms and an Afghan flag was flying at the post when it was attacked.

NATO says it is aware of the statements by Afghan officials alleging friendly fire and is investigating the incident.