An Iranian-born man with a knife injured 10 people in an attack aboard a bus in northern Germany before being overpowered by passengers and arrested by police, the local prosecutor said.

The authorities on July 20 said there was no information on the motive for the attack on a local bus in the northern city of Luebeck. They added they had no immediate indication the suspect had any links to terrorism or had been radicalized.

Officials originally said 14 people had been injured but later reduced the number. At least three were listed in serious condition.

A spokeswoman for the Luebeck prosecutor's office said the 34-year-old suspect was born in Iran but that he was a longtime Luebeck resident with German citizenship. Authorities in Germany generally do not release the names of criminal suspects.

The man has refused to speak to investigators and is scheduled to appear in court on July 21, officials said.

The prosecutor’s office said the incident began when the attacker set fire to a backpack on the bus.

The driver said he stopped the bus after seeing smoke and was attacked by the suspect.

As the assailant left the bus, he stabbed several people with a 13-centimeter kitchen knife, the driver said.

Passengers then overpowered the man outside the bus and held him for police.

Investigators said flammable liquid was found in the backpack but no explosives.

Luebeck is near the Baltic coast and northeast of Hamburg.

Based on reporting by Reuters, dpa, and AFP