A plane operated by Kazakhstan’s state security agency crashed in the Central Asian country on Saturday, killing 4 crew members and injuring 2 others, officials reported.

The 2 survivors were taken to hospital, said the ex-Soviet country’s Emergencies Ministry.

The ministry said the Soviet-built An-26 two-engine turboprop crashed while trying to land at the airport of Kazakhstan’s largest city, Almaty. The plane had flown from the capital, Nur-Sultan, with only the 6 crew members on board.

Kazakhstan’s National Security Committee said it owned the plane, noting that a probe into the cause of the crash has been launched.

The An-26 was designed in the 1960s and built in great numbers for both civilian and military use. Hundreds have remained in service in former Soviet nations and other countries around the world.