Eight people were killed Thursday when a small charter aircraft crashed while approaching a remote U.S. military-managed radar site in western Alaska, according to U.S. military officials.

The aircraft, identified as a Cessna 441 operated by Anchorage-based Security Aviation, went down at around 12:15 p.m. local time while approaching Cape Newenham Long Range Radar Site Airport. The site is located approximately 725 kilometers (450 miles) west of Anchorage.

Six passengers and two pilots were aboard the aircraft, said Clint Johnson, the Alaska region chief of the National Transportation Safety Board (NTSB).

The crash prompted a response from multiple agencies, including the U.S. Coast Guard, the NTSB, Alaska State Troopers and the Rescue Coordination Center.

Alaska Senator Lisa Murkowski expressed condolences following news of the crash. She said she had traveled extensively with Security Aviation and had met many of the company's experienced pilots.

The U.S. military described the aircraft as a civilian-contracted plane. According to the Associated Press, Lt. Gen. Robert Davis, commander of Alaskan Command, the Alaskan North American Aerospace Defense Command Region and Eleventh Air Force, said the victims were professionals carrying out a vital mission in a challenging environment.

Officials have not yet released details about the passengers' specific work at the radar facility. The site is responsible for monitoring aircraft operating in Alaskan airspace.

The Pacific Air Forces Regional Support Center manages the radar installation.