BERLIN — A man shot and killed his parents and four other members of his family then telephoned the police to turn himself in, the authorities said Friday, after the multiple killings at an inn that traumatized a small town in southwestern Germany.

The police said they had no motive for why the 26-year-old German citizen had turned his 9 mm handgun on his family at the inn in the town of Rat am See in Baden-Württemberg, where the shooter and at least some of victims were believed to have lived.

The victims included three women aged, 36, 56 and 62 and three men, aged 36, 65 and 69. Their names were not immediately released, in keeping with German privacy laws.

“We are currently working on the assumption of a domestic dispute, since all of the victims seem to be related,” said Reiner Möller, the head of the police force in nearby Aalen, at a hastily called news conference hours after the shooting.