An unmanned U.S. spy plane collecting intelligence for the war in Afghanistan has crashed, the Pentagon said Tuesday.

The Air Force RQ-1 Predator aircraft went down in Pakistan early Tuesday, Pakistan time, while it was returning to its base, officials said.

There was no indication the crash resulted from hostile fire and it was being investigated, said Cmdr. Frank Merriman of U.S. Central Command in Tampa, Fla.

It was at least the second time a Predator is known to have crashed in the region in the anti-terror campaign started after the Sept. 11 attacks on America.

In early November the Pentagon said one had crashed in bad weather. Also, in late September, before the bombing started there, the Pentagon acknowledged it had lost contact with one.

The drone can take pictures and listen to enemy communications, flying at 25,000 feet. An entire Predator system — including a ground control station and four aircraft — costs about $25 million.

Predators have seen heavy use in Afghanistan, including by the CIA, which has flown some armed with missiles on their wings to attack Taliban and Al Qaeda targets.

The larger Air Force unmanned aerial vehicle Global Hawk also has been used, making its debut in the combat zone over Afghanistan. The 44-foot-long drone can fly above 65,000 feet, see through clouds and transmit images to the battlefield in "near-real-time," according to the military.

Unmanned vehicles can fly into dangerous combat areas to gather intelligence without any threat to U.S. troops. Among other reconnaissance methods used in the war have been manned spy planes and U.S. intelligence-gathering satellites.