BERLIN (AA) - Four people were seriously injured in a knife attack at a gym in the western German city of Duisburg, authorities said Tuesday night.
Duisburg police said that they are searching for at least one suspect, but no arrests have been made yet.
It was not immediately clear whether the attack was indiscriminate or whether one or more of the victims were deliberately targeted.
Three of the victims were hospitalized with life-threatening injuries, while the other was not in critical condition, according to local media.
The police appealed for witnesses and asked anyone with information to come forward and assist the investigation.