A man with a large blade killed one and injured several more Friday at a supermarket in Hamburg, Germany, and witnesses claim he shouted "Allahu Akbar."
The man stabbed a customer to death before hurting several others as he fled, and the German newspaper Bild reports he shouted "God is great" in Arabic. Customers chased the assailant and tackled him to the ground before officers arrested him, and police said they are not sure whether this was a terrorist attack, as they have not confirmed what the killer may have said.
"We are at an early stage of the investigation," police told the BBC. "At the moment we can't rule anything out. We are investigating all avenues."
If the attacker was motivated by Islamist ideology, then this would follow a series of recent terror attacks in Germany. In December a Tunisian asylum-seeker drove a truck into a Berlin Christmas market, killing 12 and injuring 56, which motivated Germany lawmakers to tighten procedures on admitting refugees.
It is unclear whether this attacker, whose photograph was published with a white bag over his bleeding head, is a migrant. Police are in the middle of their investigation.
Early reports described his weapon as a "machete," but German police said it was likely a kitchen knife. They are not ascribing a motive to the attack currently, with German media suggesting terror and robbery as possibilities.