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

troutbait|Mi-28 helicopter crashes in Russia's Kaluga region

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.■