Police in Freiburg say the 36-year-old of Kurdish origin made a "very emotional" phone call to officers last evening after failing to show up to his trial for a narcotics offense.
He then shut himself into a cafe in an industrial area with 12 relatives, friends and acquaintances.
Police said the others were apparently well-disposed toward the man but said authorities feared he might have weapons and use them. They were negotiating with him by phone.