WASHINGTON?A U.S. military plane carrying at least seven Marines crashed into a mountain in Pakistan Wednesday night. A search and-rescue mission was launched but there was no word on casualties.

Defense Secretary Donald Rumsfeld said he understood the plane was carrying passengers.

In a brief statement, U.S. Central Command said the names of the service members were being withheld until their relatives had been informed of the crash.

Central Command, which is responsible for U.S. military operations in Pakistan and the surrounding region, said the KC-130 aircraft crashed as it was making its landing approach at a base in Shamsi in southwestern Pakistan.

At the Pentagon, Rumsfeld said he was saddened by the accident but did not know the circumstances of the crash or whether the KC-130 was on a refueling mission.