BAD AROLSEN: Authorities had yet to establish a motive on Thursday for a 29-year-old German-Armenian man who rammed his car into a group of schoolchildren in Berlin, killing a teacher and leaving another fighting for his life, but said he had no known link to terrorism.

Investigators, with the help of a translator, were trying to make sense of the "at times confused statements he was making" during questioning, Berlin's mayor, Franziska Giffey, told RBB inforadio, describing a "dark day in the history of Berlin".

The crash injured around 30 people, including 14 students, seven of whom were severely hurt and rushed to hospital after the car veered onto a pedestrian area of Berlin's busy shopping district of Charlottenburg, according to police.

Families were in mourning for the teacher who was killed while taking schoolchildren on an end of term trip to the German capital from the small town of Bad Arolsen, in the state of Hesse.

The suspect, who was naturalised as a German citizen in 2015, was previously known to the police in connection with incidents of bodily harm and trespassing, said Iris Spranger, Berlin's interior affairs minister.

Police had searched his home. State prosecutor Sebastian Buechner told reporters, "as part of the searches, medication was found and the man through his lawyers released his doctors from the secrecy obligation... so quite a lot points to paranoid schizophrenia."

The incident took place near the site of a fatal attack in 2016, when a truck rammed into a crowded Christmas market.

A witness at the scene said the driver had immediately shown remorse when confronted after the crash.

"He was surrounded by five or six men, not detained but surrounded (gestures) so that he couldn't flee," Markus Leppmeier said. "He too was injured, he had a laceration on his head, a very large bump and he kept on saying 'sorry, sorry, I did not want that, sorry.'"

FLOWERS, CANDLES AND HEAVY HEARTS

Residents of Bad Arolsen fought back tears over an incident that brought back memories of an attack in the neighbouring town of Volkmarsen, when a man rammed his car into a carnival parade in 2020, injuring dozens, including 20 children.

"It brings back lots of pictures from Volkmarsen," said Ellen Schreck, 45, whose son went to the school the group was from. She described the situation as an "absolute horror".

"It's usually a quiet little town ... you always think you're in a safe bubble here. But that's not the case anymore."

People laid flowers and candles at the Kaulbach school, which was closed on Thursday. Parents and a team from the school have travelled to Berlin to help look after the children.

"We're all deeply saddened," said Almut Will-Olivieri, who owns a pizzeria by the school. "The town is simply in shock."

Of the students who had gone to Berlin, 17 have returned to Hesse, some with their parents and others in a specially organised bus. Along with police, a team of mental health workers was working at the school to give the children support.

"This is a very difficult day for us and we have really heavy hearts," said the state premier Boris Rhein during a visit to the school.

"It will continue to have an effect for a long time to come."