A US Air Force B-52 Stratofortress crashed Monday morning at Edwards Air Force base, leaving a large plume of black smoke and rubble on the runway. 

Base officials said they believe the plane crash was not "survivable" and therefore all eight people who were on the plane are believed to be dead. 

"An Air Force B-52 Stratofortress carrying eight people on a routine mission crashed shortly after take-off," base officials said in a statement. "Initial indications are that the crash was not survivable. Emergency response personnel are on scene, and officials are working to account for all personnel."

The incident took place shortly after takeoff at approximately 11:20 a.m. local time. The airfield was closed shortly after the crash and all inbound air traffic has been diverted. 

The names and identities of the crew members were not immediately clear. The cause of the crash is still under investigation.