MOSCOW, Sept. 6 (UPI) -- A Russian MiG-31 fighter jet on a routine training flight exploded in the air and crashed in the Urals early Tuesday, killing both pilots, officials said.
Russian media report authorities said the crash occurred minutes after the plane took off from Bolshoye Savino airfield.
A Defense Ministry source told RIA Novosti a technical failure was being investigated as a possible cause.
The Defense Ministry said all MiG-31s would be grounded until the cause had been determined.
ITAR-Tass reported the jet was not carrying weapons.
A parachute found on the ground is presumed to have belonged to one of the pilots.
Investigators had "no information suggesting the plane could catch fire or explode in the air," ITAR-Tass said.
"All the circumstances of the air crash are being specified," a law enforcement official said.
The news agency reported investigators were seizing pre-flight documents.
Another Russian MiG-31 fighter crashed in November in the Perm region, but the pilots ejected safely.
