At least ten people were wounded on Friday in a knife attack that took place on a bus in Luebeck — a city in the north of Germany, said in a police press release.

"There has been an incident in a bus in Luebeck. People were injured but nobody was killed," police said in a tweet, adding that the offender is in police custody.

"The identity of the perpetrator has been clarified: a 34-year-old German citizen resident in Luebeck," police added on Twitter. "There are currently no indications the man was political radicalised and no signs of a terrorist background."

"The suspect is originally from Iran but is now a German citizen and has lived in the northern city for years", the Luebecker Nachrichten newspaper said.

Es hat in #lübeck#kücknitz einen Vorfall in einem Linienbus gegeben. Dabei wurden Menschen verletzt. Es wurde niemand getötet. Der Täter konnte überwältigt werden und befindet sich in Polizeigewahrsam. Wir sind weiterhin vor Ort und berichten auch hier weiter. — Polizei SH (@SH_Polizei) July 20, 2018

The police added that a backpack was found in the bus from which smoke was appearing. It was examined by a bomb squad, which found a "fire accelerant" but no explosives.

The exact number of injured passengers hasn't been confirmed as investigations are ongoing.