July 29 (UPI) -- The attacker who killed one person and injured six others at a German supermarket this week was a radicalized Islamist who appeared to be mentally unstable, police said.
Investigators said the 26-year-old man was known to security services as an Islamist who had become radicalized and appeared to have a "destabilized personality," but had not been considered dangerous, the Independent reported.
"We evaluated him rather as someone who was psychologically unstable than had clear Islamic extremist motivations," Torsten Voss, head of the Hamburg branch of the domestic intelligence agency, said.
The man appeared to act alone on Friday when he entered a supermarket in Hamburg and killed a 50-year-old man and wounded six others with a kitchen knife before being apprehended by citizens and arrested.
City-state interior minister Any Grote said there were no indications that the attacker was included in any terror networks or linked with background instigators.
The suspect was a rejected Palestinian asylum seeker, born in the United Arab Emirates, and had no previous criminal record in Germany, aside from a shoplifting incident in April that was dropped as a "slight" matter, Deutsche Welle reported.
Police searched a refugee shelter where the 26-year-old was believed to have been staying, but nothing was found.
Lead investigating police officer Kathrin Henning said the attacker purchased bread at the supermarket and left to get on a bus, but got off and returned to the supermarket's front door.
He then walked inside and unwrapped a brand new kitchen knife with an 8-inch blade and began "brutally" attacking a pair of men, including the 50-year-old who died at the scene.
A 50-year-old woman and five other men were wounded, including a 35-year-old man who chased the suspect and assisted in apprehending him.
Grote thanked the bystanders who helped catch the attacker before police arrived and said the arrest was "very courageous and very determined" in the face of a "nightmare" for shoppers and other citizens in the area.
Hamburg Mayor Olaf Scholz said the attack was motivated by "hate" and said the suspect's deportation had been delayed due to lack of necessary papers.
"I am furious that the offender is apparently someone who has claimed protection with us in Germany and then directed his hate against us," Scholz said. "These criminals want to poison our free society with fear, but they will not succeed."
The suspect is likely to be charged with murder and five counts of attempted murder.