ATHENS, Greece — The smell of smoke and soot pervaded Athens, with the sky darkening as a wildfire burned northeast of the Greek capital on Sunday

More than 250 firefighters, 67 fire engines, 12 planes and six helicopters are fighting the fire, which broke out around 3 p.m. local time around 35 kilometers (22 miles) from Athens.

The flames are moving fast toward Lake Marathon, an important reservoir supplying Athens with water, said Fire Colonel Vassileios Vathrakogiannis, a spokesman for the fire department. An unknown number of houses have been damaged.

Vathrakogiannis said that winds reached gale force strength in the area of the fire, and that flames exceeded 25 meters (80 feet) in height. Residents of the villages near the area of the fire have been warned by emergency text messaging to evacuate.

Another fire that broke out west of Athens has been contained, the spokesman said.

Hot and dry weather, made worse by strong winds, increases the danger of wildfires. June and July were the hottest ever recorded in Greece, which also recorded it hottest winter ever.

Both meteorologists and government officials have warned of the heightened danger of wildfires because of weather conditions from Sunday until Thursday. Half of the country will be under a “red alert,” Climate Crisis and Civil Protection Minister Vassilis Kikilias said.