(CBS) BERLIN -- A man was arrested after injuring five people with an ax at Duesseldorf’s main train station late Thursday, police said, correcting earlier police reports of two arrests.

German police said there was a single perpetrator, who is severely injured in a hospital. The perpetrator has not been identified.

Of the five people who were injured in the attack, one of them is in life-threatening condition, police said.

The motivation for the attack is unclear, CBS News correspondent Mark Phillips reported from London. No fatalities were reported.

Earlier, a spokesman for federal police, who are usually in charge of policing train stations, had said two people were arrested and further attackers might be on the run.

A spokeswoman for Duesseldorf police Anja Kynast said officers are searching the station and its surroundings, but that they do not have concrete information about further attackers at this stage.