One person dead. Homes and buildings charred. Huge tracts of forestland destroyed, the burned area leaving a thick scar covering nearly 25,000 acres northeast of Athens, the Greek capital, according to European satellite images.

Although the Greek authorities said on Tuesday that the threat to Athens posed by major wildfires that tore through its northern suburbs a day earlier had diminished, the damage caused has been “massive,” Vasilios Vathrakogiannis, the country’s fire service spokesman, said in a telephone interview.

And the true extent of the damage cannot be accurately assessed until the fires are completely doused, he said.

Several factors turned favorable for firefighters working to contain the blazes, which began on Sunday in Varnavas, a town about 20 miles northeast of Athens, before being whipped by strong winds into several fronts.

The presence of Lake Marathon in the heart of the fires meant that firefighting aircraft were able to reload water there rather than flying to the sea and back, Mr. Vathrakogiannis said, and a lull in strong winds overnight aided the efforts. Until that point, he said, “As firefighters were putting out the fires, sparks were setting new ones behind them.”