The president of the American University in the Afghan capital says a militant attack is underway on the campus.

Mark English tells The Associated Press that security forces are on the scene after Wednesday's attack and that "we are trying to assess the situation."

Witnesses say they heard explosions and automatic gunfire. It was not immediately clear if anyone was wounded.

Police spokesman Sediq Sediqqi says police and intelligence agency personnel are at the campus, on the western outskirts of Kabul. He says police believe there is just one assailant.

The attack comes two weeks after two university staff were kidnapped from their car by unknown gunmen. Their whereabouts are still unknown.