Eight people have been killed after a small plane chartered by the U.S. Army Corps of Engineers crashed near a remote military radar site in western Alaska.

The crash occurred around midday on Thursday near the Cape Newenham Long Range Radar Site Airport, approximately 450 miles (725 kilometres) west of Anchorage. The twin-engine Cessna 441 had departed from Ted Stevens Anchorage International Airport and was heading towards the remote facility.

The victims comprised two pilots and six passengers. Two of those killed were employees of the U.S. Army Corps of Engineers, who were part of a project delivery team travelling to a project site in support of the U.S. Air Force. Their identities had not immediately been released.

U.S. Air Force Lt. Gen. Robert Davis described the incident as a “devastating loss” for the military community, saying those on board were professionals carrying out an important mission in a demanding environment.

Reports indicate that foggy weather was present around the time of the crash, although investigators have not determined whether weather or any other factor caused the aircraft to go down. The National Transportation Safety Board (NTSB) and Federal Aviation Administration (FAA) are investigating the incident.

Alaska Senator Lisa Murkowski said the flight was operated by Security Aviation, an Anchorage-based charter company. She expressed condolences to the victims’ families and commended the agencies involved in the search and recovery operation.

The Cape Newenham facility is a private military site and forms part of a network of remote radar installations used to monitor aircraft operating in Alaska’s airspace and along its borders.

Investigators are expected to examine the aircraft, flight data, communications and weather conditions as they work to determine the cause of the fatal crash.