Bavaria’s top security official says a Syrian asylum seeker who blew himself up late on July 24 outside of a music festival in the southern German town of Ansbach had "pledged allegiance" to militants who call themselves Islamic State (IS).
Meanwhile, the Aamaq News Agency -- which is seen as a mouthpiece for IS militants and operates in territory controlled by IS extremists -- said on July 25 that the attack was carried out by an IS "soldier."
Bavarian Interior Minister Joachim Hermann said on July 25 that video of the suicide bomber pledging allegiance to IS was found on his cell phone.
Hermann said the attacker had vowed to take "revenge against the Germans" for what the suicide bomber claimed was "obstructing Islam."
The 27-year-old from Aleppo, Syria blew himself up after he had been refused admission to the music festival because he did not have a ticket. He killed himself and injured at least 12 people -- three of them seriously.
Hermann said the man was carrying a backpack filled with explosives and metal parts that could have killed many people.
"The obvious intention to kill more people indicates an Islamist connection," Hermann said.
Police on July 25 raided the attacker's refugee hostel and confiscated items that authorities said could be used to build more bombs -- including fuel and hydrochloric acid.
Authorities also found literature related to Salafism -- the ultra-conservative reform movement within Sunni Islam that is espoused by IS militants and Al-Qaeda-linked extremist groups.
A suspected accomplice of the suicide bomber, who had claimed to have known the attacker only in his capacity as a translator, also was arrested early On July 25.
Police evacuated more than 2,000 from the music festival after the explosion and cordoned off the area.
The attacker, whose name has not been disclosed, had repeatedly received psychiatric treatment that included counseling for attempted suicide, Herrmann said.
The attacker had been living in Ansbach for the last two years, but his asylum request had been rejected in Germany.
He was scheduled for deportation to Bulgaria -- the first European Union member country where he registered for asylum.
But authorities said his deportation had been suspended because of his "psychological instability."
Herman said the attacker was previously known to police because of a drug-related offense and other crimes.
Germany is on edge following several violent incidents in the past week linked to IS or to asylum-seekers.
Earlier on July 24 an asylum-seeker from Syria killed a woman with a machete and injured two other people in Germany's southwestern city of Reutlingen before being arrested by police.
An 18-year-old German-Iranian shot dead nine people in Munich on July 22.
On July 18, a 17-year-old asylum-seeker thought to be from Afghanistan or from Pakistan wounded five people on a train using an ax and knife.