Pakistani police say an unmanned U.S. spy plane has crashed near an air base used by American forces in their battle against terrorists in neighboring Afghanistan.

Officials say no one was hurt by the crash Sunday. The aircraft went down near Pakistan's southern city of Jacobabad, about 200 kilometers from the Afghan border.

The cause of the crash is unknown, and U.S. officials have not commented on the incident. A number of drones have gone down in the area since U.S. military forces began using remote-controlled reconnaissance planes in the region three years ago.