The pilots from a Ka-52 Alligator helicopter, which crashed while approaching to land in Moscow on Tuesday, had not ejected but left the helicopter on their own after the impact, a source aware of the situation told Interfax-AVN.

While the helicopter was approaching to land at a pad belonging to an aircraft manufacturing plant in Moscow, it started rotating uncontrollably, the source said. The pilots did what they could to land the helicopter, but it still hit the ground and partially disintegrated.

The crew comprised of a captain and co-pilot left the helicopter after it hit the ground themselves, the source said. He denied that the pilots had ejected before the crash.

"The captain was practically unhurt, but the co-pilot suffered serious injuries," the source said.

Both pilots have been transported to a hospital, he said.