Berlin's top security official has said the latest information suggests the driver of a car that hit pedestrians in the German capital on Wednesday was "mentally ill".
Iris Spranger was speaking after a Renault Clio drove into a school group, killing a teacher and seriously injuring at least nine other people.
Six of those injured are reported to be in a life-threatening condition.
Investigators are now trying to make sense of “confused” statements by the suspect after the incident.
The driver has been identified as a 29-year-old German-Armenian who lives in Berlin. He was detained swiftly after his car came to a halt in a shop window.
According to reports, the man was subdued by passers-by before being arrested. He has also been hospitalised.
Spranger added that the woman killed was a teacher on a trip to the German capital with students from a secondary school in the central German state of Hesse.
Berlin Mayor Franziska Giffey said on Thursday that the incident was a "case of a mentally ill person running amok".
Spranger said on Wednesday that posters were found in the car “in which [the suspect] expressed views about Turkey.” But she said there was “no claim of responsibility.”
German Chancellor Olaf Scholz has also condemned the man's actions as a "cruel rampage".
Giffey added that the incident brought back “terrible memories” of a truck attack more than five years ago at the nearby Breitscheidplatz square.
A memorial service for the people killed or hurt in Wednesday's crash was held in the evening at the Kaiser Wilhelm Memorial Church on the Breitscheidplatz, next to the scene of the crash.