At least 27 people have died in fires which have ravaged forests in northern and central Portugal over the past 24 hours, rescuers said Monday, as three people were killed in neighboring Spain in blazes sparked by arsonists.

In Portugal, Prime Minister Antonio Costa asked for international help and declared a state of emergency as more than 4,000 firefighters fought some 20 major fires still raging Monday.

The 27 deaths, confirmed by Portugal’s national civil protection agency, came four months after 64 people were killed and more than 250 injured on June 17, in the deadliest fire in the country’s history.

About 520 separate fire outbreaks on Sunday were caused by “higher than average temperatures for the season and the cumulative effect of drought, which has been felt since the start of the year”, civil protection agency spokeswoman Patricia Gaspar said.

In the northwestern Spanish region of Galicia, on the Portuguese border, authorities were blaming arson for about 17 fires which have caused three deaths.

“They are absolutely intentional fires, premeditated, caused by people who know what they are doing,” said Alberto Nunez Feijoo, the head of the Galicia regional government.

On Monday, the “situation remained very worrying”, Feijoo said, adding that firefighters along with soldiers and locals were battling the flames.

Spanish Interior Minister Juan Ignacio Zoido said in a tweet that “several people have been identified in connection to the fires in Galicia”.

The fires were being fanned by wind gusts of up to 90 kilometers per hour as Hurricane Ophelia moved north off the coast of Spain towards Ireland, Zoido told private broadcaster La Sexta.

“We have not had a situation like this in the past decade. We have never deployed so many means at this time of the year,” he said.