MADRID — A raging forest fire enveloped a stretch of road in central Portugal this weekend, killing more than 60 people, including at least 30 motorists who were trapped in their cars.
The fire, which was still burning on Sunday afternoon, has brought “a dimension of human tragedy that we cannot remember,” Prime Minister António Costa said during a visit to the scorched area around Pedrógão Grande.
The initial deadly blaze started on Saturday, and the flames spread along four fronts with “great violence,” said Jorge Gomes, the secretary of state for internal administration. By Sunday afternoon, five infernos were raging in central Portugal, he said.
The death toll stood at 61, according to Lusa, the national news agency. Officials said they expected the toll to rise.
Half of the people killed died in their cars, Mr. Gomes confirmed, after being hemmed in by the flames while driving along a road through the densely forested area between Figueiró dos Vinhos and Castanheira de Pêra.
Officials said they had found 17 bodies near the road, possibly those of people who had tried to escape on foot once they realized there was no way to continue driving. Two people were also killed in a car crash related to the fire.
Several houses were destroyed by the flames. Portuguese television showed people scrambling to leave their homes in the early hours of Sunday morning, escorted by firefighters and other rescue teams, as huge flames engulfed hamlets across the dry, cracked terrain.
Several roads were cut off by flames and thick smoke as firefighters tried to prevent the fires from spreading.
About 1,600 firefighters, assisted by airplanes and helicopters, were working to contain the damage. The police and military units were called in to help, and European Union officials in Brussels activated the bloc’s civil protection mechanism to send reinforcements. Spain sent two planes to help contain the fires.
An investigation into the cause of the fires is likely to look into why motorists were left stranded on the road, and whether the authorities cut off all of the access roads quickly enough to prevent drivers from inadvertently heading toward the blaze.
The cause of the initial fire near Pedrógão Grande was not immediately clear. Officials had suggested that it was started by lightning during a dry thunderstorm, in which lightning strikes but there is no rain.
José Maria de Almeida Rodrigues, the national director of Portugal’s judicial police, told Lusa on Sunday, “Everything points very clearly toward natural causes.”
Portugal, where summer wildfires are common, has been experiencing a heat wave for several days, with temperatures climbing above 100 degrees Fahrenheit, or 40 degrees Celsius.
And though Portuguese fire experts said on Sunday that it was difficult to say for sure how the fires had spread so rapidly, environmentalists warned that the country needed to urgently improve its forest management and fire monitoring.
Domingos Xavier Viegas, a fire expert who is a professor at the University of Coimbra, said the speed of the fire’s progression suggested that it had started simultaneously in different places and that its advance was probably aided by the gorges and ravines that cut through the area’s terrain. They can help fires progress, Mr. Xavier Viegas told Lusa, creating new pockets of fire that “easily catch people by surprise.”
Wildfires are very unpredictable, firefighting experts say, especially when high temperatures, low humidity and a particularly dry landscape create a vast tinderbox in large wooded areas.
“We know fire behavior has changed and continues to change, yet we continue to be surprised every time, when we shouldn’t be,” said Don Whittemore, a former assistant fire chief in Colorado who has studied wildfire behavior. “The notion that firefighters will be able to put out, suppress or make safe a wildfire is becoming less and less of a reliable notion.”
João Branco, the president of Quercus, an environmental association, said that the fires in Portugal reflected “a situation of negligence” and a flawed approach to forestry that has led to the large-scale replacement of pine trees with eucalyptus trees in areas around Pedrógão Grande. Eucalyptus contains an oil that burns easily. Mr. Branco said that the government had regularly promised to improve Portugal’s forestry policies, but that instead, “everything continued in the same way.”
The Portuguese branch of the World Wildlife Fund said the devastating fires should serve as another urgent reminder that the government needed to improve its forestry management.
“Responsible forestry management is more effective and financially more efficient than the huge mechanisms used every year to combat forest fires,” WWF Portugal said in a statement.
The blaze around Pedrógão Grande is Portugal’s worst forest fire in more than half a century. In 1966, 25 soldiers died while trying to put out a fire in the hills near Sintra.
Patrícia De Melo Moreira, a photographer for Agence France-Presse based in Lisbon, accompanied firefighters on Sunday to the road where drivers had been stranded.
“They were just trying to control the fire and stop it from spreading because it was just so huge,” she said by telephone. “Many clearly died in their cars, and the road was completely destroyed, melted.”
Ms. De Melo Moreira later made her way to villages in the fire zone, where residents had been alerted to the advancing blaze.
“People are just standing outside, staring, trying to see if the fire could be getting closer to their houses,” she said. “Everybody is very worried, but also pretty calm.”
President Marcelo Rebelo de Sousa paid tribute to the firefighters early on Sunday, saying they faced the toughest conditions possible: “temperature, wind and zero humidity.”
He spoke of the “human warmth” and solidarity displayed by people caught in the tragedy, and sent a message of “gratitude, comfort and support to all those who have been doing the best that they can.”