BERLIN (AP) — Three villages southwest of Berlin have been evacuated as a wildfire the size of 400 soccer fields spread Friday.

More than 500 people had to leave their homes as a result of the fire in Treuenbrietzen, some 50 kilometers (31 miles) outside of Berlin.

"Our main goal is to protect the evacuated villages from the flames," local lawmaker Christian Stein told the German news agency dpa.

"We haven't been able to push back the fire, but none of the buildings have been damaged."

Police said that their plans to douse the flames have been complicated by old ammunition from World War II, that was still buried in the forests and which could explode due to the fires.

The fire started Thursday afternoon. By the evening, the authorities had evacuated the villages of Frohnsdorf, Klausdorf and Tiefenbrunnen.

Overnight, winds blew the smoke to Berlin, where people in some neighborhoods were asked to keep their windows closed. Berlin emergency services received calls from concerned Berliners.

Hundreds of firefighters were on the ground in Treuenbrietzen trying to cut trees to make long swaths in the forests to prevent the fire from spreading further. They were also fighting the flames with helicopters and water cannons.

Germany has seen a long, hot summer with almost no rain and large parts of the country are on high alert regarding possible wildfires.

"I hope the weather will play along and the winds won't increase again," Stein said. "We are yearning for rain."