A man armed with a knife has attacked people on a bus in the northern city of Luebeck on Friday, injuring several including one seriously before he was arrested.
The local Luebecker Nachrichten newspaper, without citing its source, said the attacker was a 34-year-old man originally from Iran who now had German nationality and had lived in Luebeck for years.
The interior minister of Schleswig-Holstein, the state where Luebeck is located, did not assume there was a terrorist motive, the local paper added. Prosecutors later said he was refusing to speak with investigators.
"The exact number of injured is still unclear. There were no dead," the police and prosecutor's office said in a statement. "The background to the crime is still unclear and the subject of the ongoing investigation."
The Nachrichten reported at least 14 people were wounded, two seriously.
On Twitter, the police said the attacker was overpowered and taken into police custody.
"We ask for your understanding that we cannot provide any information about the identity of the suspect at the moment," the police added on Twitter. "It is important to us to only disclose reliable information in order not to fuel speculation and not to obstruct the investigation."
"The bus was full," the police added, appealing to passengers who fled the scene to contact them.
The newspaper cited state prosecutor Ulla Hingst as saying: "Nothing can be ruled out, including a terrorist background."
"One of the victims had just given up his place to an older woman, when the attacker stabbed him in the chest," Luebecker Nachrichten, which said the attacker appeared to be in his mid-30s, quoted a witness as saying.
An area around a bus stop in the Luebeck neighbourhood of Kuecknitz was sealed off by police, spokesman Dierk Duerbook told Bild.
Earlier, police in Schleswig-Holstein tweeted that there was a major police deployment under way in the city.