A police probe into Wednesday’s tragedy had shown “it was the act of a severely mentally impaired person,” Franziska Giffey told public broadcaster RBB, adding that investigators were still trying to decipher the perpetrator’s “confused statements” with the help of an interpreter.

Investigators have yet to determine whether posters with reference to Turkey that were found in the man’s car offered clues as to the motives of the man, who is of Armenian descent.

The man drove into a group of school children and their teacher – visiting from a small town in the central state of Hesse – on a street corner before getting the car back on the road and crashing into a shop window further on.

Giffey referred to a “dark day in Berlin’s history.”

“I am deeply saddened by this horrific crime,” German Chancellor Olaf Scholz wrote on Twitter late Wednesday.

“The trip of a Hessian school class to Berlin ended in a nightmare. Our thoughts are with the relatives of the dead and the injured, including many children. I wish them all a speedy recovery,” he wrote.