What is known about the US Air Force bomber crash that left 8 dead in California

Eight people, including two Boeing employees, died after a US Air Force B-52 bomber crashed immediately after taking off from Edwards Air Force Base in Southern California.
The incident occurred at 11:20 am local time (15:20 GMT) on Monday (15/06), while the aircraft was carrying out a routine test mission. The crash sent a huge plume of black smoke into the air that could be seen from miles away.
"Today, Edwards Air Force Base suffered a terrible tragedy, and we lost eight great Americans," said Col. James Hayes, describing them as "a group made up of military, civil servants and government contractors."
The base had previously reported that initial indications were that the crash had "no survivors." The victims' families were still being notified and their names will be released 24 hours after that, Hayes said.
The crash was "fully contained" inside Edwards Air Force Base on the runway, Hayes said, and the base temporarily suspended operations.
The B-52 was supporting the base's radar modernization program, he said, and crashed immediately after takeoff, catching fire. After analyzing the initial images, the incident was considered "an irreversible accident with no survivors", said Hayes.
No cause has been determined at this time, and this will only be possible after a series of investigations, which could take up to 30 days. Further investigations could extend for more than six months, Hayes said.
Boeing confirmed in a separate statement that two of its employees were among the occupants and said the company is in contact with their families. The company did not provide further information after contact from the BBC.
California Governor Gavin Newsom called the crash "a tragic incident" and expressed condolences to the victims' families and the Edwards Air Force Base community in a post on "Buff", which is in part an abbreviation for "Big Ugly Fat".
The B-52 is a long-range strategic bomber that has participated in attacks in the US and Israeli war on Iran.
Capable of flying at up to 15,000 meters - compared to commercial airliners, which fly at around 10,000 meters - the payload of the enormous 32,000 kg bomber can include hundreds of conventional bombs and 32 nuclear cruise missiles.
The aircraft can refuel mid-flight, giving it a potentially unlimited attack range. This created a "nuclear umbrella" for the US during the Cold War era of mutually assured destruction in the mid-20th century.
The planes typically carry a crew of five - aircraft commander, pilot, radar navigator, navigator and electronic warfare officer.
Edwards Base is located about 100 miles north of Los Angeles in the Mojave Desert.

Source: G1