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A raging forest fire killed dozens in Portugal by Circa News
Global News

At least 61 people have been killed in a raging forest fire in central Portugal, officials said Sunday. 

Portugal’s prime minister, António Costa, described the blaze as "the greatest tragedy we have seen in recent years in terms of forest fires." He declared three days of national mourning in response to the massive fire.

WATCH  | Sérgio Fonseca captured this view Sunday afternoon of Figueiró dos Vinhos, one of the towns affected by the wildfire in Portugal (via CNN). 

Investigators found a tree that was hit during a "dry thunderstorm" and said a lightning strike in  Pedrogao Grande, which is about 95 miles from the country's capital, likely sparked the blaze Saturday. 

A "dry thunderstorm" is a storm that produces thunder and lightning, but precipitation evaporates before reaching the ground because of high temperatures. Portugal and other southern European countries are prone to forest fires in the dry summer months. 

"The dimensions of this fire have caused a human tragedy beyond any in our memory," Costa told reporters when he arrived at the scene Sunday. "Something extraordinary has taken place and we have to wait for technicians to properly determine its causes."

He added that the death toll is likely to rise as officials begin searching isolated homes for more bodies. 

The Associated Press contributed to this report.