The man arrested for Thursday night’s fatal stabbing near the Erasmus bridge in Rotterdam is a 22-year-old from Amersfoort, police said on Friday moring.

A 32-year-old man from Rotterdam was stabbed to death in the incident and a 33-year-old Swiss national was seriously injured.

The suspect was also injured when he was overpowered by bystanders, one of whom was a personal trainer who hit him several times with a stick. Police say the suspect “was known to them” but would not comment further.

Eyewitnesses told the police that the suspect had shouted “Allahu akbar” as he stabbed the second victim but this has not been confirmed. They also said the man appeared to be determined to attack more people.

Police have not yet said anything about a possible motive.

The personal trainer, who was giving a lesson under the bridge, described the chaotic scene as the suspect tried to get into a nearby cafe.

“I saw him stabbing a young lad with two long knives… and I ran at him using a squat stick I use for lessons,” said Reniël. “I broke it in two and began to run and scream at him,” he said. “People were keeping him out of the cafe with chairs and I was able to hit him a couple of times.”

Rotterdam police are appealing for more witnesses to come forward.