MOSCOWplaytoearncryptogamesaxieinfinity, July 25 (Xinhua) -- A Russian Mi-28 helicopter crashed during a routine flight in the Kaluga regionplaytoearncryptogamesaxieinfinity, killing its crew onboard, the Russian Ministry of Defense said in a statement on Thursday.

The crash occurred in an uninhabited area, causing no damage on the ground, the ministry said, adding that the preliminary cause of the crash appears to be a technical malfunction.

The Mi-28 helicopter is a Russian-made, twin-seat attack helicopter.■