A Russian Mikoyan MiG-31 fighter jet crashed in the Urals on Tuesday, killing both pilots, officials say. The jet exploded in a fireball minutes after taking off from a military airport in the Perm region in the early hours of Tuesday. It was on a routine training flight, a spokesman for the Russian Defense Ministry said. A technical failure is being investigated as the possible cause of the crash, a source in the ministry told RIA Novosti. A similar jet crashed in the region last year, but the pilots managed to parachute to safety. All MiG-31s have been grounded following the accident. The Defense Ministry said the ban would remain in place until the cause of the disaster had been established.