Officials in Kazakhstan say a military helicopter has crashed on a training flight, killing all 13 people on board.

The Defense Ministry said the helicopter went down Wednesday in the Zhalagash region in southern Kazakhstan, east of the Aral Sea.

It added that the Mi-8 helicopter was part of a formation flying from Aktau on the Caspian Sea to Shymkent near the border with Uzbekistan, as part of special forces' drills.

The ministry said it wasn't immediately clear if there were any survivors, but Kazakhstan's interim President Kassym-Jomart Tokayev later tweeted that all those aboard have died.

Tokayev said he ordered an official probe into the crash's reason.