Eight people are thought to have died after an American B-52 bomber crashed shortly after take-off from a military base in California.
The plane, a B-52 Stratofortress, crashed just after taking off from Edwards Air Force Base in Kern County, California on Monday morning.
The eight people killed in the crash were a combination of US Air Force personnel, Government civilians and Government contractors, the US Air Force said at a press conference.
A statement from Edwards Air Force base the bomber crashed at 11.20am PDT (7.20pm BST) and emergency crews immediately responded to the scene.
"The airfield has been closed, and all inbound aircraft are being diverted," Edwards Air Force Base added.
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Next of kin notifications are currently underway, and identities of the deceased are being withheld.
Non-commercial visitor passes to the bases were suspended until further notice - with the base now allowing people to visit after initial recovery operations concluded.
Shortly after 11pm BST, a statement from the base said the bomber was carrying eight people on board.
"Initial indications are that the crash was not survivable," it confirmed.
PICTURED: Smoke billows into the sky at Edwards Air Force Base after the horror crash
|X/SCOPEREPORT_
Initial images from Fox News showed a large plume of black smoke surrounding the wreckage.
Edwards Air Force Base went on to confirm the crash was under investigation.
"Our thoughts and prayers are with the families and unite members at this time," the California base added.
Operations are currently grounded at Edwards Air Force base and will be throughout Tuesday.
The downed bomber is said to have been the 60-0061, according to Air Force airmen and veterans online.
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Emergency services responded to the crash, which was determined to be 'not survivable' by Edwards Air Force Base
|REUTERS
The Air Force confirmed the bomber was being used to test the B-52's state-of-the-art radar modernisation programme.
The nuclear-capable B-52 first entered service in the 1950s and remains a key bomber in the US Air Force's arsenal.
The aircraft is one of 76 B-52s in the Air Force's fleet.
The California base is the US Air Force's main flight test centre, with B-52s stationed there frequently used for developmental and modernisation testing.
PICTURED: Black smoke was seen far from the site of the Air Force base, located in the desert north of Los Angeles, California
|REUTERS
An effort to upgrade the B-52 is currently underway, with Boeing winning a $2billion contract from the US Air Force to provide new engines and systems to the bombers.
Equipped with a new Rolls-Royce engine, the upgraded aircraft will be designated as the B-52J to extend the bomber's lifespan until 2050.
Before Monday's crash, the most recent fatal incident was in 2008 as six US Air Force personnel were killed as they crashed their B-52 into the Pacific Ocean off the coast of Guam while preparing for a flyover.
The B-52 is no longer being manufactured, with replacement parts sourced from dismantled airframes, stored at Davis-Monthan Air Force Base, Arizona.
In 2016, bombers were used in about 1,800 combat sorties against Isis forces in Syria and Iraq.