The fire broke out on Saturday in the municipality of Pedrogao Grande in central Portugal, apparently caused by a lightning strike, and spread furiously in several directions.
Nearly 900 firefighters and 300 vehicles were still battling the blaze on Sunday afternoon as scenes of devastation could be seen around the town.
“Unfortunately, this seems to be the greatest tragedy we have seen in recent years in terms of forest fires,” said a visibly moved Prime Minister Antonio Costa, who declared three days of mourning starting on Sunday.
He said it was vital to focus on the prevention of new fires, amid a continuing heat wave, strong winds and lack of rain. He also warned that the death toll could still increase
The expanse of wooded hills in the area north of Lisbon, which 24 hours before had glowed bright green with eucalyptus plants and pine trees, was gutted by the flames.
A thick layer of white smoke hovered over either side of a motorway for about 20 kilometers (12 miles), as blackened trees leaned listlessly over charred soil.
A burnt-out car sat outside partly destroyed and abandoned houses, while a few meters away police in face masks surrounded the corpse of a man hidden under a white sheet.
Police chief Almeida Rodrigues blamed dry thunderstorms, ruling out arson and saying a tree had been struck by lightning.
“Everything burnt very quickly given the strong winds. The flames passed within two or three kilometers of my house,” said local resident Isabel Ferreira, 62.
“I knew several of the victims. One of my colleagues lost her mother and her four-year-old girl as she could not get them out of the back of the car.”
Secretary of State for the Interior Jorge Gomes said 62 people burned to death, mostly trapped in their cars engulfed by flames.
“It is difficult to say if they were fleeing the flames or were taken by surprise,” he said.
More than 50 people were injured, five critically, including one child and four firefighters.
Portugal was hit by a series of fires last year which devastated more than 100,000 hectares (1,000 square kilometers) of the mainland.
Fires on the tourist island of Madeira in August killed three people, while across 2016 around 40 homes were destroyed and 5,400 hectares of land burned.
In 1966, a blaze in the forest of Sintra, west of Lisbon killed 25 soldiers trying to battle the flames.