Emergency services were called to the scene in Schmalkalden at about 0200 GMT on Monday by a resident who reported hearing unusual noises. Six houses and 25 people were evacuated.

Thuringia state's environment and geology office said it wasn't immediately clear why the ground gave way. The crater measures 98 feet by 98 feet (30 meters by 30 meters). It said it was possible that rock formations underground broke up, creating a cavity.

Authorities plan to fill the hole with gravel.