Greece's Fire Service announced that two helicopters collided while taking part in efforts to extinguish a major wildfire in the Psatha area, about 60 kilometres west of central Athens.
In a statement, the Fire Service said a rescue operation is currently under way to locate the crews of the two helicopters.
Both crew members from one of the two firefighting helicopters that collided on Sunday in the Greek area of Psatha, west of Athens, died in the incident, Greece's Fire Service said. The second crew were rescued alive, it said
Greece has been battling wildfires for the past week, with more than 12,000 hectares of forests and agricultural land destroyed.
The collision underscored the continuing danger at the most volatile front of Europe's wildfire emergency.
The continent's crisis split into three stark fronts: strong winds drove flames deeper into the Athens region and forced fresh evacuations, France guarded a still-burning scar four times the size of Paris, and Spain's major fires stopped advancing.
The most immediate danger was in Greece. Flames spread through western Attica, the region around Athens, threatening communities and an industrial district outside Megara as violent gusts prevented firefighting aircraft from collecting water from the sea.
The danger carried grim resonance in a region where the 2018 Mati wildfire killed 104 people, Europe's deadliest blaze this century.
Farther west, containment brought no end to the emergency. France's largest wildfire remained held within its perimeter after forcing 224,000 people to flee in what may have been the country's largest civilian evacuation outside wartime.
Agencies