The ministry said the Su-24 bomber crashed today as it was approaching its base in the southern Volgograd region on a regular training mission. It said a search mission was underway to locate the crew.
The Russian air force has temporarily grounded its Su-24 fleet pending an investigation into the crash, according to a Defense Ministry statement carried by Russian news agencies.
The twin-engine Su-24 has been a mainstay of both the Soviet and Russian air force since the 1970s.