Eight dead in B-52 bomber crash in California

Eight people died when a US B-52 bomber crashed and erupted into a catastrophic fire shortly after takeoff at an air force base in California, officials said.

The heavy bomber was on a routine testing mission with a mixture of military, government and civilian contractors on board when it came down at Edwards Air Force Base, 95km north of Los Angeles.

Footage of the aftermath of the crash, which officials said was "unsurvivable," showed a large charred patch of ground on which almost nothing remained of the huge plane manufactured by Boeing.

"Edwards Air Force Base experienced a horrible tragedy, and we lost eight great Americans," Colonel James Hayes told reporters at the base.

Col Hayes said the B-52 Stratofortress - a long-range bomber used by the US military since the 1950s - was on a test sortie as part of a radar modernisation process.

"It took off, and immediately after takeoff, crashed and burst into flames," he said, adding emergency services quickly swung into action, but soon determined that there would be no one to rescue.

"After reviewing the footage of the crash, it was deemed that this was an unrecoverable crash and unsurvivable."

In the aftermath of the crash, the airfield was closed and all inbound aircraft were being diverted, the base said on social media.

Boeing said two of those killed were employees of the company and it expressed its condolences to families of all the victims.

The B-52 is a heavy bomber that first flew in 1954 and was originally designed for war with the Soviet Union.

It has received continual upgrades to keep it in service for decades since the Cold War's end.

The massive bomber - which can carry a range of weapons, including bombs and cruise missiles - has a wingspan of 56 metres and a length of 48 metres.

The plane is usually crewed by five people: an aircraft commander, a pilot, a radar navigator, a navigator and an electronic warfare officer, according to a US Air Force fact sheet on the plane.

The plane is also capable of carrying a nuclear payload.

The United States has deployed the aircraft in conflicts in Vietnam, the Gulf, Iraq, Afghanistan, and, most recently, in Iran.