Police said 12 people were wounded, including three seriously, in the attack in Ansbach, a small town of 40,000 people southwest of Nuremberg that is also home to a U.S. Army base.

The incident will fuel growing public unease surrounding Chancellor Angela Merkel's open-door refugee policy, under which more than a million migrants have entered Germany over the past year, many fleeing wars in Afghanistan, Syria and Iraq.

"It's terrible that someone who came into our country to seek shelter has now committed such a heinous act and injured a large number of people who are at home here, some seriously," Bavarian Interior Minister Joachim Herrmann told reporters at a hastily convened news conference early on Monday.

"It's a further, horrific attack that will increase the already growing security concerns of our citizens. We must do everything possible to prevent the spread of such violence in our country by people who came here to ask for asylum," he said.

Herrmann said it was unclear if the man, who arrived in Germany two years ago and tried to commit suicide twice before, had planned to kill only himself or "take others with him into death".

It was the fourth violent incident in Germany in a week, including the killing of nine people by an 18-year-old Iranian-German gunman in Munich on Friday.

REUTERS