BAELEN, Belgium — Firefighters battled a massive wildfire in eastern Belgium on Sunday that has burned more than 27 square kilometers (10 square miles) in the High Fens, a large nature reserve, and forced nearby residents to evacuate in what media describe as one of the worst-ever wildfires in the country’s recent history.

About 600 residents in nearby municipalities in Waimes and Bütgenbach, in Liège province near the German border, were told to evacuate Saturday as winds shifted and smoke spread through the area. Authorities also advised tourists to leave, while a nearby gymnasium was opened to receive evacuees.

Liège provincial Gov. Hervé Jamar said in a statement Sunday that more than 250 emergency personnel have been deployed, including over 100 Belgian and German firefighters, police and military officers and civil protection staff, helped by firefighting helicopters operated by Belgium’s federal police and the Netherlands,

Authorities said no homes had been affected as of Sunday morning, though the fire remained close to residential areas and heavy smoke persisted. They urged people to stay away from the fire zone, warning that unnecessary traffic could obstruct emergency vehicles and complicate firefighting operations.

The fire follows weeks of unusually hot and dry weather. The High Fens’ mix of heathland and peat bogs has complicated efforts to contain the flames.

In the nearby town of Monschau, in Germany, local authorities warned overnight that the fire was about 3 kilometers (2 miles) from the border and said firefighters were on alert. Early Sunday morning, the town website recommended that people in three outlying districts near the border leave the area temporarily because officials couldn’t rule out health risks caused by smoke.

Belgium was hit by another spell of intense heat this week, with temperatures reaching about 37 C (98.6 F) in parts of the country Friday.

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Corbet reported from Paris. AP writer Geir Moulson in Berlin contributed.