The knife attacker, a refugee from Eritrea, had injured another male passenger and a policewoman, the police reported on Wednesday. He was then shot and killed by the officer who happened to be on the train.
Bild newspaper reported that the assailant stabbed the male passenger after getting into an argument with him. The man survived but sustained serious injuries.
The policewoman had tried to settle the dispute between the two men but was hurt after confronting the attacker. She eventually fired her weapon to take the attacker down.
A motive for the attack was still unclear on Thursday. The 24-year-old refugee lived in North Rhine-Westphalia and is believed to have had a temporary German residence permit, police in Schleswig-Holstein said. He reportedly entered Germany via Austria in September 2015.
There were no initial indications of a possible Islamist attack, according to information gathered by DPA. A police spokesman said that he was “not aware” as yet of any connection to terrorism.
Interior Minister Horst Seehofer said he was “deeply upset” by the attack. “Violence must never be tolerated, be it against the public or against the police,” he said.
The intercity train was on its way to Flensburg from Cologne via Hamburg. According to the federal police, the incident occurred around 7 pm when the train was still about 20 kilometres away from Flensburg train station.
The station was temporarily evacuated and the area around it was closed off on Wednesday, but travellers could access it again later in the evening.