Lisbon, Portugal ? Wildfires flared again around Portugal’s third-largest city Wednesday, just hours after firefighters brought them under control after fighting a dozen blazes this week.

More than 540 firefighters supported by 150 fire trucks and seven air tankers were battling blazes in the Coimbra district alone. They also were working in the central and northern districts of Porto, Santarem, Vila Real, Viseu.

Four more people were arrested Wednesday on suspicion of arson – raising to 122 the number of people detained this year on suspicion of deliberately starting fires. Eighty people were arrested last year for arson in Portugal.

Portugal has had little or no rain for 10 months, with at least 75 percent of the country suffering through an extreme drought, the Water Institute said.

French firefighters, who interrupted their vacations to travel to Portugal, join firefighters battling a forest fire in Miranda do Corvo, near Coimbra, 120 miles north of Lisbon. Wildfires that have been raging for days were briefly brought under control Wednesday before they flared up again, officials said.

After days of fires, a cooling fog and higher humidity helped firefighters bring the flames under control Wednesday before they flared up again, officials said.

The fire has destroyed at least 10 houses in the suburbs of the city of Coimbra, about 120 miles north of Lisbon. About 50 residents were evacuated Tuesday night.

Wildfires have killed 15 people, 11 of them firefighters, this year, burning through 445,000 acres, compared with 320,370 acres last year.

Other parts of southern Europe also were ablaze. In Spain, enduring its driest year since keeping rainfall records in the 1940s, dozens of fires were burning in the northwest Galicia region and other areas.