AVELAR, Portugal (AP) -- Raging forest fires in central Portugal killed at least 58 people, many of them trapped in their cars as flames swept over a road, in what the prime minister on Sunday called "the biggest tragedy of human life that we have known in years."
 
Nearly 60 other people were injured, including four firefighters and a seriously injured minor, Interior Ministry official Jorge Gomes told state broadcaster RTP.
 
A lightning strike is believed to have sparked the blaze in the Pedrogao Grande area after investigators found a tree that was hit during a "dry thunderstorm," the head of the national judicial police told Portuguese media.
 
Dry thunderstorms are frequent when falling water evaporates before reaching the ground because of high temperatures. Portugal, like most southern European countries, is prone to forest fires in the dry summer months.
 
"This is a region that has had fires because of its forests, but we cannot remember a tragedy of these proportions," said Valdemar Alves, mayor of Pedrogao Grande. "I am completely stunned by the number of deaths."
 
Authorities had previously said that 40 C heat in recent days might have played a part in the inferno about 150 kilometers northeast of Lisbon. About 700 firefighters have been trying to put out the fires since Saturday, Gomes said.
 
A huge wall of thick smoke and bright red flames towered over the top of trees near houses in the wooded region. Local resident Isabel Brandao told The Associated Press that she had feared for her life.
 
"Yesterday we saw the fire but thought it was very far. I never thought it would come to this side," she said. "At 3:30 a.m., my mother-in-law woke me up quickly and we never went to sleep again. We were afraid the fire would reach us."
 
RTP showed terrifying images of several people on a road trying to escape the intense smoke that had reduced visibility to a question of a few meters (yards). A young man shared a bottle of water with a distraught woman as she stumbled down the road.
 
Gomes said that at least 30 people were killed when their vehicles were engulfed by flames on a road between the towns of Figueiro dos Vinhos and Castanheira de Pera, and three others died from smoke inhalation in Figueiro dos Vinhos. The rest of the bodies were found outside of the cars or in the forest, the official said.
 
The official also said that firefighting crews were having difficulties in battling the fire, which was "very violent" in at least two of its four fronts.
 
The European Union said it had activated its civil protection efforts responding to a call for assistance by Portuguese authorities. EU Commissioner for Humanitarian Aid and Crisis Management Christos Stylianides expressed his condolences for the victims in a statement, saying the "EU is fully ready to help."
 
As a result, a Spanish firefighting aircraft was already assisting on Sunday morning and another one was expected to arrive later in the day. France was also sending three aircraft.
 
Prime Minister Antonio Costa said that firefighting crews were having difficulties in approaching the area because the fire was "very intense." 
 
On Sunday, Costa also tweeted his "deepest regret for the victims... and a word of encouragement and strength for all who help combat this scourge."
 
The loss of life due to forest fire was the biggest in memory in Portugal. It has been over 50 years since 25 Portuguese soldiers perished fighting wildfires in 1966.
 
Last August, an outbreak of fires across Portugal killed four people, including three on the island of Madeira, and destroyed huge areas of forest.
 
Portugal's civil protection agency, which coordinates firefighting efforts, issued a warning of the increased risk for forest fires in Friday. Citing the high temperatures, it said that all outdoor fires were prohibited.
 
Many world leaders, including French President Emmanuel Macron, Pope Francis and Indian Prime Minister Narendra Modi, expressed solidarity with Portugal.
 
Spanish Prime Minister Mariano Rajoy tweeted that he is "overwhelmed by the tragedy at Pedrogao Grande. The Portuguese people can count on our solidarity, support and care."