More than 40 firefighters with 20 fire engines and three water-dropping helicopters battled the fire, which broke out in Kalamos, a coastal area some 45 km northeast of Athens.
“The fire is big, there are a lot of houses in the area,” a fire brigade official told Reuters.
Police said no injuries had been reported but at least three houses were damaged heavily. Television footage showed residents with hoses struggling to save their homes.
Greek authorities ordered a precautionary evacuation of two youth camps in the area.
The cause of the fire was unknown, but summer wildfires are common in Greece. Hundreds died in 2007 during the most serious outbreak in decades.
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