A wildfire has burned over half of a historic nature preserve in Belgium near the country’s border with Germany, triggering explosions and evacuations in multiple nearby villages.

The wildfire, which started on Aug. 13 and was 0% contained as of Tuesday afternoon, has burned over 3,000 hectares (7,413 acres) of the around 5,000-hectare High Fens nature preserve, the oldest preserve in Belgium. The fire has also reportedly caused multiple explosions due to unexploded WWII-era munitions in the forest, according to German fire crews at the scene.

“The authorities are asking residents and visitors to strictly respect the barriers and access restrictions,” the East Belgium Tourist Agency said in a press release. “This is essential to ensure that emergency and response teams can work without obstruction.”

Air quality has quickly deteriorated throughout the region, with the burning of the preserve’s peat bogs, heathland and pine forests producing unhealthy levels of smoke in the Belgian cities of Bütgenbach, Jalhay, Malmedy and Waimes, along with the nearby areas in Germany, according to IQAir.

“It is therefore recommended to keep windows and doors closed,” the tourism agency said. “Due to changing wind directions, it is currently not possible to estimate in the long term which areas will be particularly affected.”

The European Union deployed two planes and six helicopters following the activation of the civil protection mechanism. EU space monitoring agency Copernicus is working to provide a rough estimate of the fire’s size, along with fire extent and damage assessment emergency mapping.