Interior Ministry official Jorge Gomes said 60 people died from the flames and suffocating smoke, while another two people perished in a traffic accident related to the fires. The victims were caught in the fire as they tried to flee, officials said.
According to news reports, the fast-moving wildfires ripped through the forested Pedrógão Grande central region of Portugal, some 150 kilometers (95 miles) northeast of Lisbon, leaving dozens dead and more injured.
On Sunday afternoon, almost 900 firefighters and 300 vehicles were still battling the blaze as scenes of devastation could be seen around the town.
"The dimensions of this fire have caused a human tragedy beyond any in our memory", said Prime Minister Antonio Costa told reporters on his arrival at the scene Sunday.
Costa said that while investigations are ongoing to determine the cause of the fire, authorities believe that the high temperatures of 40 Celsius in recent days may have played a part.More news: Worth the Upgrade: The new iPad Pro
The death toll was cut from 62 to 61 after a counting error, "but we will certainly find other victims on the ground" in searches from village to village, said Costa.
Portugal has declared three days of national mourning as the death toll in one of the country's worst forest fires rises to 62.
Around 600 firefighters were trying to put out the blazes, which started on Saturday.
Spain has sent two water-bombing planes to help their neighbour fight the fires.
A Spanish firefighting aircraft is assisting and another is expected to arrive later on Sunday, while France is also sending three aircraft.More news: US congressman Scalise still in critical condition: hospital
On Sunday, Pope Francis led thousands of people in silent prayer for the victims of what he called the "devastating fire", while the Portuguese football team offered its "deepest sympathies to the families, friends and loved ones of the victims of the fires".
An alert issued by Portugal's National Authority for Public Safety on Friday warned of an enhanced risk of wildfire ignition and spread due to the hot, windy weather.
Mariano Rajoy has tweeted that he is "overwhelmed by the tragedy at Pedrogao Grande". He said authorities were anxious about strong winds that could help spreading the blaze further.
A stream in Penela reflects the wildfire raging in central Portugal on Sunday.More news: A glance at the Senate's Iran, Russia sanctions legislation
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