Residents of the seaside resort town of Artemida in east Attica were evacuated on Thursday afternoon to allow three water-dropping helicopters to assist the work of the fire-fighters.
The blaze broke out at about 1.30 p.m. near the Arionos Avenue.
Sixty-five firemen with 15 fire engines are operating in the area, assisted by volunteers and equipment provided by municipal authorities.
A separate fire in Neos Voutzas, near a 10th century monastery on the eastern slope of the Penteli Mountain in northeastern Attica, was brought under control.
The fire department said the blaze was contained quickly.