Hundreds of firefighters battled to put out wildfires across southern Europe on Thursday, some of which are believed to have been set deliberately by arsonists and stoked by an extended heat wave gripping the region.

The dangerous heat is the result of a large high-pressure system drawing in warm, dry air over the Continent, and it could last through at least Monday in some places.

ATHENS, Greece (AP) — Wildfires intensified across southern Europe on Wednesday after a nightlong battle to protect the perimeter of Greece’s third-largest city, with at least three more deaths reported in Spain, Turkey and Albania.