Five bodies were found in two cars outside an Italian restaurant, while a sixth man died on the way to hospital.
A German police spokesman said the victims, aged between 16 and 39, had all been shot in the head.
All six were linked to a clan involved in a long-running and deadly feud in Italy's Calabria region, police said.
The dispute is known as the San Luca feud after the village where it began back in 1991.
Police sources said all six men were linked to the infamous Calabria-based 'Ndrangheta crime group. [from BBC.co.uk]