Gunman in Afghan police uniform kills 3, wounds several

An individual wearing an Afghan police uniform opened fire on a group of civilians in western Afghanistan on Sunday, killing three civilians and wounding several others, a senior U.S. military official confirmed to NBC News.

The casualties included Americans and the shooter was also killed, officials said.

The civilians were contract workers for NATO's International Security Assistance Force. They were working at a regional training center for Afghan security forces based in Herat but there was no word yet on their specific job duties.

It wasn’t immediately known if the shooter was an actual police officer, the official said.

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