Fire has torn through suburbs north of Athens, destroying homes and forcing thousands to flee in night-time evacuations.
The fires came within 12 miles of downtown Athens and blackened thousands of acres of land covered by pine forest or thick bush.
The army removed anti-aircraft missiles from a military base as flames approached.
"The situation is tragic. Fires are out of control on many fronts," greater Athens local governor Yiannis Sgouros said. "Athens had an area of greenery that now has gone."
He said an estimated 30,000 acres of land had been burned.
A state of emergency was declared in greater Athens. It is the most destructive fire seen in Greece since fires in the south of the country killed more than 70 people in 2007.
Firefighting planes and helicopters from France, Italy and Cyprus were due to arrive later, government officials said.
Planes and helicopters resumed water drops following an eight-hour pause that allowed the wildfire to spread across parts of Mount Penteli and reach suburban homes. Clouds of black smoke filled the capital's skyline and obscured the sun.
Authorities evacuated two large children's hospitals, campsites and homes in villages and outlying suburbs threatened by blazes that scattered ash on streets across the city.
Deputy Fire Chief Stelios Stefanidis said no casualties had been reported by early on Sunday, despite the overnight evacuations of hundreds of hillside homes. The fires, which started late on Friday, were reported in an area more than 25 miles wide.
