ATHENS, Greece (AP) — Thousands of residents fled to safety from a wildfire that burned for a fourth day north of Athens early Friday, during an overnight battle to stop the flames reaching populated areas, electricity installations and historic sites.

In heat wave conditions, the blaze tore through forest areas 20 kilometers (12.5 miles) north of the capital, destroying more homes. Ground crews of several hundred firefighters dug fire breaks and hosed the flames.

Traffic was halted on the country's main highway connecting Athens to northern Greece, as crews tried to use the road as a barrier to stop the flames advancing before water-dropping planes could resume at first light. But sparks and burning pine cones carried the fire across the highway at several points.

Several firefighters and volunteers were hospitalized with burns, health officials said.

“We are going through the 10th day of a major heat wave affecting our entire country, the worst heat wave in terms of intensity and duration of the last 30 years,” Fire Service Brig. Gen. Aristotelis Papadopoulos said.

Nearly 60 villages and settlements were evacuated Thursday and early Friday across southern Greece, with weather conditions expected to worsen.

Fires were raging on the island of Evia, northeast of Athens, and at multiple locations in the southern Peloponnese region where a blaze was stopped before reaching monuments at Olympia, birthplace of the ancient Olympic Games.

A summer palace outside Athens once used by the former Greek royal family was also spared.

Fire crews and water-dropping planes and helicopters from five European countries were due to arrive Friday and through the weekend as the European Union stepped up support to fire-hit countries in southeast Europe. The heat wave also has fueled deadly fires in Turkey and across the region.