German prosecutors said Thursday there was no indication of a terrorist motive in a knife attack on a train that killed two teenagers and wounded several other passengers.

A 33-year-old suspect, a stateless man of Palestinian origin, has been detained over the stabbing spree that occurred Wednesday on a train travelling between the northern cities of Hamburg and Kiel.

"There are no indications of a terrorist background," Peter Mueller-Rakow, a spokesman for the local prosecutor's office, told AFP.

The investigation into the attack and the suspect's history was ongoing, he added.

A 16-year-old girl and a 19-year-old man were killed in the attack and seven people injured.

Passengers helped overpower the suspect and restrained him until police detained him at a railway station in the town of Brokstedt.

The suspect, who has no fixed abode, was only recently released from prison in connection with an assault case, police said.