On Friday evening, a man ploughed a car into a crowd of shoppers at a Christmas market in the German city of Magdeburg.
The attack killed five people, including a nine-year-old boy, and left more than 200 injured, with many in a critical condition.
A judge has ordered the pre-trial detention of a 50-year-old man arrested on suspicion of carrying out the attack.
Police believe he acted alone.
At 19:02 local time (18:02 GMT), the first call to emergency services was made.
The caller reported that a car had driven into a crowd at a Christmas market in the middle of town.
The caller assumed it was an accident, police said, but it soon became clear this was not the case.
The driver, police said, had used traffic lights to turn off the road and onto a pedestrian crossing, leading him through an entry point to the market which was reserved for emergency vehicles, injuring a number of people on the way.
Unverified footage on social media showed the driver speeding the vehicle through a pedestrian walkway between Christmas stalls.
Eyewitnesses described jumping out of the car's path, fleeing or hiding.
Police said the driver then returned to the road the way he came in and was forced to stop in traffic. Officers already at the market were able to apprehend and arrest the driver here.
Footage showed armed police confronting and arresting a man who can be seen lying on the ground next to a stationary vehicle - a black BMW with significant damage to its front bumper and windscreen.
The entire incident was over in three minutes, police said.
A nine-year-old boy and four women aged 45, 52, 67 and 75 are confirmed to have died in the attack.
More than 200 people have been injured and at least 41 of those are in a critical condition.
The toll had earlier been reported as two dead and 68 injured, but was revised to the much higher totals on Saturday morning.
None of the victims have been identified yet.
"The reports from Magdeburg raise the worst fears," German Chancellor Olaf Scholz said on social media platform X.
Magdeburg's city councillor for public order, Ronni Krug, said the Christmas market will stay closed and that "Christmas in Magdeburg is over", according to German public broadcaster MDR.
That sentiment was echoed on the market's website, which in the wake of the attack featured only a black screen with words of mourning, announcing that the market was over.
The Saudi government expressed "solidarity with the German people and the families of the victims", in a statement on X, and "affirmed its rejection of violence".
UK Prime Minister Sir Keir Starmer said he was "horrified by the atrocious attack in Magdeburg", adding that his thoughts were with "the victims, their families and all those affected" in a post on X on Friday night.