MUNICH — A 21-year-old refugee from Syria killed a woman with a kebab knife in southwestern Germany on Sunday and was arrested after a motorist deliberately ran him down, according to the police. It was the nation’s second major act of violence carried out by an asylum seeker in a week.

The man, whose identity was not released, had been involved in at least one previous violent episode, according to officials in Reutlingen, where the afternoon attack occurred near the central bus station.

“At this time, we suspect this crime is linked to relationship troubles,” Michael Schaal, a police spokesman, said. “Witnesses have told us that before the attack, they had argued.”