A Syrian migrant, denied asylum in Germany a year ago, set off an explosive device near an open-air music festival in the country’s south, killing himself and wounding a dozen others, authorities said Monday, the third attack to hit the region in a week.

The 27-year-old had spent time in a psychiatric facility, but the authorities said a jihadist motive for the attack on Sunday night appeared “likely.”

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

Germany is reeling after nine people died in a shopping center shooting rampage in Munich on Friday and four people were wounded in an axe attack on a train in Wuerzburg on July 18.

All three attacks were in Bavaria, which has been a gateway for tens of thousands of refugees under German Chancellor Angela Merkel’s liberal asylum policy.

Police said the man intended to target the music festival but was turned away because he did not have a ticket, and set off the explosive device outside a nearby cafe.

“My personal view is that it is very likely that this was a real Islamist suicide attack,” regional interior minister Joachim Herrmann said.

“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,” Herrmann told 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 told Reuters the recent attacks raised serious questions about Germany’s asylum law and security across the country and said he planned to introduce measures at a Bavarian government meeting on Tuesday to strengthen the police forces and ensure they have adequate equipment.

Herrmann said the man arrived in Germany two years ago and had been in trouble with local police repeatedly for drug-taking and other offences.

He said investigators had yet to determine the motive of the attacks. “Because the rucksack and this bomb were packed with so many metal parts that could have killed and injured many more people, it cannot simply be considered a pure suicide attempt.”

Interior Minister Thomas de Maiziere cautioned Germans against indiscriminately branding all refugees a security threat after the rash of attacks over the last week.

“We must not place refugees under general suspicion despite individual cases that are under investigation,” he said in an interview with the Funke media group.

Merkel’s deputy spokeswoman Ulrike Demmer later expressed the government’s “shock” after the rash of violence but also warned against labelling all refugees.

“Most of the terrorists who carried out attacks in recent months in Europe were not refugees,” she said.

“This fact corresponds with ongoing investigations indicating that the terrorism threat (among refugees) is not larger or smaller than in the population at large.”

Meanwhile, police said they have arrested a 16-year-old Afghan in relation with the deadly rampage at the Munich mall.

Police said the teenager was a friend of the 18-year-old German-Iranian attacker who killed himself after the rampage Friday night.