Hundreds of firefighters battled a major wildfire west of Athens Monday using water-dropping planes and helicopters, a day after a helicopter collision killed two crew members.

The collision laid bare the danger at the most volatile front of Europe’s wildfire emergency. Flames bore down deeper into the region of the Greek capital, forcing fresh evacuations in the early hours of Monday. In France, firefighters guarded a still-burning scar four times the size of Paris.

The two crew members – one Greek and one Danish national – died when their helicopter collided with another near the seaside area of Psatha while tackling the fire that started Friday morning.

The blaze raged through pine forests and scrubland through the weekend, whipped by gale-force winds that often prevented water-dropping planes from operating.

The crew of the second helicopter – a Greek and a British national – were taken to a hospital, where their injuries were reported to be light. Foreign firefighting and helicopter crews are often deployed in Greece to help tackle wildfires during the country’s hot, dry summers.