At least 57 people have died and and 59 others, including six firefighters, have been injured in forest fires that broke out on Saturday night, BBC reported. Officials said most of the victims were driving by when they got caught amid the rapidly spreading flames and smoke in the mountainous region of Pedrogao Grande.

Secretary of State for the Interior Jorge Gomes said that 30 of those who died were found inside cars, and another 17 next to the vehicles. Among the 59 injured was an eight-year-old girl found wandering close to the fire.

About 60 forest fires broke out across the country overnight, with close to 1,700 firefighters battling them. While Spain has sent waterbombing planes to put out the fires, the European Union is also coordinating an international firefighting effort.

The cause of the fires is not yet known, though thunderstorms and could be responsible. The country has also been reeling from the effects of a heatwave, with the mercury soaring above 40 degrees Celsius on Saturday.

“Unfortunately, this seems to be the greatest tragedy we have seen in recent years in terms of forest fires,” said Prime Minister Antonio Costa.

“The number of fatalities could still rise,” The Guardian quoted Costa as saying at the Civil Protection headquarters near Lisbon. “The priority now is to save those who could still be in danger.”