Two helicopters have collided in Greece as they were battling to control wildfires.

Video of the incident some 65 km (42 miles) west of the capital, Athens, shows one of the helicopters hitting the propellers of the other, which bursts into flames. Both fell into a ravine. Two of the four crew members involved were found unconscious, Greek media report, with the others sustaining light injuries.

Several fires have broken out in Greece this week, prompting many people to leave their homes. Strong winds have hampered efforts to bring the blazes under control.

Several other European nations have suffered devastating wildfires after a succession of heatwaves created favourable conditions for them.

Early this week, France and Spain battled huge fires – two of the main ones were close to Madrid and Bordeaux respectively. Those have now been contained, though they are still burning. Some 300,000 people who were evacuated have started to return to their homes.

In Greece, media reports describe “a titanic battle” along a swathe of territory that includes Porto Germeno, Psatha, Fokida, Megara and Kefalonia, where more than 500 firefighters have been struggling to bring the situation under control over the past 72 hours.

The mid-air collision occurred “during a forest firefighting operation in the Psatha area,” the Fire Department announced.

The crew members – two Greek and two Romanian, according to Greek media – have been taken to the 251st Air Force General Hospital.

Most wildfires are sparked by people, whether intentionally or accidentally, but climate change is making the conditions for them more common.

Last winter was mild and wet, encouraging vegetation growth, which has then dried out in successive hot spells, generating fuel for wildfires.