Lutz Katschmann of Thuringia state's environment and geology office said it wasn't immediately clear why the ground gave way.

Six houses and 25 people were evacuated.

A still image taken from Reuters video shows a crater that appeared in the early hours in the central German town of Schmalkalden.

Emergency services were called to the scene in Schmalkalden at about 3am local time.

A huge crater measuring 30 by 40 metres has opened up in the middle of a residential estate.

A general view of a large crater that appeared during the early hours in the central German town of Schmalkalden.

A crater about 20 metres deep has opened up in a residential area of an eastern German town - swallowing a car and a garage door but causing no injuries.

Emergency services were called to the scene in Schmalkalden at about 3am local time on Monday by a resident who reported hearing unusual noises. Six houses and 25 people were evacuated.

Lutz Katschmann of Thuringia state's environment and geology office said it wasn't immediately clear why the ground gave way, the German news agency DAPD reported.

The crater measures 30 metres by 30 metres.

Katschmann said it was possible that rock formations underground broke up, creating a cavity.

Authorities plan to fill the hole with gravel.