Search teams have recovered the bodies of six Americans who died when their plane crashed high in Afghanistan's snow-covered mountains, U.S. military officials said Wednesday.

The plane went down Saturday, but search efforts were complicated by bad weather and difficult terrain, said military spokesman Maj. Mark McCann.

"We regret to report that all six individuals on board the aircraft — the three U.S. civilian crew members and three U.S. soldiers — were killed in the crash," McCann said.

He said the victims' identities would be released later by the Defense Department and Florida-based Presidential Airways (search), which had contracted the CASA 212 (search) transport plane to the U.S. Air Force.

A plane carrying the bodies of the six victims back to the United States left Bagram on Tuesday evening, bound for Dover Air Force Base (search) in Delaware, McCann said.

"An investigation will be conducted to determine the cause of the crash. However, at this time, we have no indication this crash was caused by hostile fire," McCann said.

The bodies were found amid the debris of the plane in the Hindu Kush mountains, southeast of Bamiyan.

"They found pieces of the engine and the wheels scattered on top of Baba Mountain," which rises to 5,060 meters [16,600 feet] and was covered in fresh snow, said Ghulam Mohammed, a senior police official in Bamiyan.

McCann said the plane's flight recorder had been retrieved, but it was not clear what it showed about the crash.

He said the plane crashed en route to Farah, in western Afghanistan. However, a senior U.S. general said it was headed for Shindand, 60 miles further north.

"The indications we have is that it got into a valley and tried to gain altitude quickly," Maj. Gen. Eric Olson told The Associated Press. "The pilot apparently recognized that we was not going to be able to gain altitude quickly enough and tried to make a very dramatic turn, didn't make it and crashed into a very narrow valley."

The fixed-wing CASA 212 is designed to fly in and out of the kind of short, rough air strips used to supply American forces deployed in remote areas of the country to search for Taliban and Al Qaeda militants.

Accidents have accounted for most of the more than 100 deaths of U.S. service members since Operation Enduring Freedom began in the wake of the Sept. 11, 2001, attacks on the United States.

McCann said the bodies of the six Americans will be returned to their families "as soon as possible."