Eight people aboard a US Air Force B-52 bomber are believed to have died after the aircraft crashed shortly after take-off from Edwards Air Force Base in the US state of California on Monday, the Air Force said.
The bomber was carrying eight people on a routine test mission when it crashed late Monday morning, according to a statement from the base.
"Initial indications are that the crash was not survivable," the Air Force said in a release, adding that emergency response personnel were at the scene and officials were working to account for all personnel.
The cause of the crash is under investigation.
Earlier, Edwards Air Force Base said on Facebook that emergency services had responded immediately to the accident and temporarily closed the military airfield, diverting incoming aircraft to other airports.
B-52 aircraft are long-range bombers used by the US Air Force and are capable of carrying both conventional and nuclear weapons.
Edwards Air Force Base is located around 100 kilometres north of Los Angeles in the Mojave Desert.
In the past, the US military has used the base to test, among other things, stealth drones and jets capable of travelling at six times the speed of sound.
A press conference was scheduled for later on Monday.
