ANSBACH, Germany -- A Syrian man who exploded a suicide bomb outside a music festival in southern Germany was a rejected asylum seeker who was slated to be deported to Bulgaria, officials said.
Twelve people were injured in Sunday night's blast in Ansbach, three of them seriously, Bavarian Interior Minister Joachim Herrmann said at a news conference Monday. The bomber, who has not been named, was killed.
Authorities said he was a 27-year-old Syrian known to police who entered Germany two years ago.
He had applied for asylum, and his application was rejected about a year ago. But he was not sent back to Syria, as German policy does not allow rejected applicants to return to war zones.
Instead, under the auspices of the Dublin Regulation -- a European Union law governing states' responsibility for asylum seekers -- the attacker was supposed to be deported to Bulgaria, the country where he had entered the EU, said Johannes Dimroth, spokesman for Germany's Federal Interior Ministry.
Dimroth said he did not know why the deportation had not been carried out, saying it was a matter for Bavarian state authorities.
Music festival targeted
The bombing, the fourth attack in southern Germany in a week, took place at the final concert of the Ansbach Open music festival Sunday night, where about 2,500 were in attendance, police said.
At about 9:45 p.m. Sunday, security staff at the concert noticed a suspicious person wearing a backpack pacing up and down around the entrance to the event, a police statement said.
The man had been denied entry into the concert since he did not have a ticket, according to Hermann.
The police statement said that the bomber "lingered around in the outdoor seating area of a nearby wine restaurant."
"An explosion took place at around 10:10 p.m. in that area after the young man briefly leaned forward, according to eye witness accounts," it said.
The music festival and surrounding area were then evacuated.
Herrmann said the attacker's backpack contained screws and nails in an apparent bid to inflict widespread damage.
Attacker's home searched
Bavarian state police are searching where the attacker lived in a hotel being used as a refugee shelter, according to spokesman Michael Petzold.
He said the motive for the attack was not clear, but authorities were working to determine whether it was Islamist-related, and to determine whether the explosives were homemade.
The bomber was known to police in Ansbach for previous offenses, including drug crimes, Herrmann said. He had also twice attempted suicide before the bombing.
"Because how this backpack and the bomb were packed, especially with so many metal splinters, which could have killed and injured many more people, this act cannot be purely assessed as a suicide," Herrmann said.
The attack has not been confirmed as terrorism, Hermann said, but there are strong indications it may be.
Ansbach, with about 40,000 people, is a major U.S. military garrison town, with around 5,000 members of the military living there along with civilians, contractors and retirees. There are three military installations in the Ansbach area, according to the garrison's website.
String of attacks
The Ansbach bombing is the third attack in the southern German state of Bavaria in recent days.
The spate of violence has rattled the country and fueled criticism of Chancellor Angela Merkel's immigration policies, with the hashtag #Merkelsommer, or "Merkel summer," circulating on social media.
A week ago, a 17-year-old who had arrived in Germany as an unaccompanied minor from Pakistan or Afghanistan carried out a stabbing attack on a train in Wurzburg, about 45 miles from Ansbach.
The attack, which authorities said appeared motivated by ISIS propaganda, has left four people in hospital, including one in an induced coma, medical officials said.
On Friday, an 18-year-old with dual German and Iranian nationality went on a shooting spree in a busy shopping district in the Bavarian capital, Munich, killing nine people before killing himself.
Police said the gunman was a mentally troubled individual who was obsessed with mass shootings and may have planned the attack for a year. Authorities have not found a link to terror groups.
And on Sunday, hours before the Ansbach attack, a 21-year-old Syrian asylum seeker killed a woman with a machete in Reutlingen in the neighboring southern German state of Baden-Wurttemberg.
The attacker had come to Germany a year ago, according to a police, and was known to authorities for property thefts and assault. The woman was 45 and from Poland, police said.
Police: Teen who knew Munich gunman arrested
Police announced Monday the arrest of a 16-year-old Afghan national who knew the Munich gunman, and had met with him shortly before the rampage, officials said.
Chief prosecutor Thomas Steinkraus-Koch said that, when police interviewed the teen Friday night in the aftermath of the attack, he deleted a WhatsApp chat log of his conversations with the attacker.
But police have since been able to recover the chat log, which showed the teen knew the gunman had munitions, leading authorities to suspect the teen may have known about the attack ahead of time.
The two teens, both loners who played a lot of first-person shooter games, had met while receiving inpatient psychiatric care last summer and had exchanged messages discussing their fantasies of going on rampages, officials said.
The 16-year-old had known that the gunman was obsessed with Anders Behring Breivik, who killed 77 people in Norway in 2011. The Munich attack was carried out five years to the day since Breivik's rampage.
Hermann Utz of the Munich criminal investigation department said the 16-year-old's apartment had been searched. The teen will appear before a judge Monday.
Minister: 'Very terrible week' in Bavaria
Speaking at a press conference Monday, Hermann, the interior minister, acknowledged it had been a "very terrible week" in the Bavarian state.
"Yes, this was also for me personally a very terrible week, as I think it was for most of the people in Bavaria. The attack last Monday on the train in Wurzburg, then the rampage ... in Munich Friday night, and now again an attack.
"It has been almost nine years now that I am interior minister. And I have not had, thank goodness, to experience something like this during these nine years until now. And I do hope that I will not experience something like that so soon and fast."