At least 27 people have been killed and over 50 injured since Sunday in a series of wildfires in central and northern Portugal, the country’s National Civil Protection Authority said on Monday.

Firefighters were still tackling 145 wildfires, 32 of which were serious, a spokeswoman for the agency said. There were around 500 fires on Sunday, the worst day of the year so far in terms of the number of simultaneous fires, The Portugal News reported. The country had seen another massive set of forest fires in June, which had killed 64 people.

“We can confirm the deaths of 27 people in the districts of Coimbra, Castelo Branco, Viseu and Guarda,” Patricia Gaspar of the civil protection agency said.

The fires were likely caused by unusually high temperatures over the weekend. Prime Minister António Luís Santos da Costa has declared a public calamity for districts north of River Tagus.

News agency Reuters had earlier reported that some of the fires had been started deliberately, and strengthened by strong winds brought by the tail end of the Hurricane Ophelia. Casualties were also reported from north-western Spain.