Nearly 500 firefighters, 120 vehicles, three planes and four helicopters swung into action from dawn to battle the flames from spreading to the suburbs of Penteli, Pallini, Anthousa and Gerakas, which is home to some 29,000 people.
No injuries were immediately reported but at least 10 homes are believed to have sustained varying degrees of damage, state TV ERT said.
"The sky was red...we left without taking anything with us," a Pallini resident who lost his car and shed to the flames told ERT.
The house next door was completely gutted.
"The civil protection authority was late in alerting us. The fire was scorching our backs, we left in the nick of time. Had we stayed another 30 seconds it would have burned us," he said.
Greek media reported that an 80-year-old man in Anthousa had fatally shot himself in despair over the fire, which broke out on Tuesday afternoon.
Greece has so far been spared the scorching temperatures that have contributed to deadly wildfires in France, Portugal and Spain, destroying vast tracts of land, but has faced gale-force winds this week.
The wildfires on the foot of Mount Penteli north of Athens were fanned overnight by strong winds that constantly changed direction.
"There are two active fronts...the winds are so strong that the planes are prevented from making targeted water drops," senior civil protection official Vassilis Kokkalis told Athens 98.4 radio.
He added that the fire was threatening businesses on a major Athens highway.
"It's a fire that will be a cause for concern for several days because of rekindlings," Kokkalis said.
Residents in several areas, a paediatric hospital and the national observatory at Athens were evacuated as a precautionary measure.
The police said some 600 people had been moved to safety overnight.
"It was insane, we did not know where to flee," an elderly resident of Anthousa told ERT.
"Embers were falling from the sky, I've never seen anything like it," he said.
Traffic was suspended on parts of a ring road around Athens, the company that manages it said on Twitter.
Greece has set up a crisis cell and firefighters battled 117 wildfires in the country in the last 24 hours.
Another 87 firefighters were battling a blaze in the Peloponnese, a southern peninsula.
Athens has asked European countries to send firefighters. A heatwave and wildfires last year destroyed 103,000 hectares (255,000 acres) and claimed three lives.
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