An American was attacked in western Germany by a man who shouted "Heil Hitler," police said Thursday.

The attacker confronted the 54-year-old American for speaking in English with a woman at a McDonald's restaurant in Gelsenkirchen, in the industrial Ruhr region, police said.

The man demanded to know why the two were not speaking German. The woman said her friend did not speak German well, and the American asked, "What's your problem?"

Police said the assailant then said: "We are in Germany. German is spoken here," before shouting "Heil Hitler" and raising his right arm. The Hitler salute is illegal in Germany.

The American, who was not identified, threatened to call police. As he reached for his cell phone, police said, the stranger head-butted him, and he fell to the floor. The assailant then repeatedly kicked his left ankle.

The attacker fled and the American was taken to a hospital for treatment, police said.

Police released two video surveillance photos showing the suspected assailant and appealed to witnesses to come forward.