Two crew members were killed and two others rescued after two firefighting helicopters collided while battling a wildfire in western Attica on Sunday, Greek authorities said.

According to the Greek Fire Service, the leased Bell helicopters were taking part in efforts to contain a wildfire in the Psatha area when they collided midair and crashed, triggering an immediate search and rescue operation.

Rescue teams later located all four crew members.

Two were pulled from the wreckage alive, while the other two were found unconscious and later confirmed dead.

The victims were identified as a Greek coordinator and a Danish pilot.

The survivors, a Greek coordinator and a British pilot, were taken to the 251st General Air Force Hospital in Athens for treatment.

The fire service said each helicopter was carrying a two-member crew consisting of a foreign pilot and a Greek coordinator.

Shortly after the collision, the pilot of one of the helicopters managed to contact the Fire Department’s operations centre and reported that the other crew member had been injured.

The crew of that aircraft was later found with minor injuries and was able to communicate with rescuers.

The helicopters had taken off from Elefsina Air Base before joining the firefighting operation.

Authorities have launched an investigation to determine the cause and circumstances of the midair collision.