Eight people died when a US B-52 bomber crashed and erupted into a catastrophic fire shortly after take-off at an air force base in California on Monday, 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 in a huge fireball at Edwards Air Force Base, 95km (60 miles) 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.“Edwards Air Force Base experienced a horrible tragedy, and we lost eight great Americans,” Colonel James Hayes told reporters at the base.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 take-off, 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.”