Turkey faced a “very risky week” for wildfires, an official said Monday, as blazes across parts of southeast Europe and the Balkans damaged homes and led to a huge firefighting operation that included evacuations.

Wildfires that have engulfed Turkey for weeks spread rapidly overnight, threatening Bursa and forcing 3,500 to flee. Greece and Bulgaria are also contending with fires.

Wildfires have engulfed Turkey for weeks, threatening Bursa, the country’s fourth-largest city and forcing over 1,700 people to flee.