A passenger jet crashed in Pakistan early Wednesday morning, killing all 152 people aboard in the worst plane crash in the country's history. Two of the victims were American citizens, the U.S. Embassy in Islamabad reported.

Rescue workers faced a macabre scene as the crash sight was strewn with body parts and twisted metal wreckage. Parts of the plane were hanging from trees and scattered across the forest.

"The situation at the site of the crash is heartbreaking," said Imtiaz Elahi, chairman of the Capital Development Authority, which deals with emergencies and reports to the Interior Ministry. "It is a great tragedy, and I confirm it with pain that there are no survivors."

Airbus A321, operated by Airblue, was trying to land in the rain when it went down in the hills surrounding the Pakistani capital of Islamabad. The pilots reportedly did not send any emergency signals before going down.

"I'm seeing only body parts," Dawar Adnan, a rescue worker with the Pakistan Red Crescent, said by telephone from the crash site. "This is a very horrible scene. We have scanned almost all the area, but there is no chance of any survivors."

So far, rescuers have managed to recover nearly 80 bodies from the wreckage.

The cause of the crash isn't clear, but officials said they do not suspect terrorism. Airblue spokesman Raheel Ahmed said an investigation would be launched into the cause of the crash.