A driver ploughed into people in a busy shopping area in the centre of the German city of Leipzig on Monday afternoon, leaving two people dead, authorities said.
An additional three people were seriously injured in what officials believe was a deliberate rampage, Mayor Burkhard Jung said.
He described it as “a terrible tragedy”.
An unspecified number of people sustained less serious injuries.
The driver, a 33-year-old German citizen, was detained in the car. Police said he was a German-born resident of the Leipzig area.
Prosecutors said he is under investigation on suspicion of murder and attempted murder.
There was no immediate word on a possible motive.
The interior minister of Saxony state, Armin Schuster, said investigators believe the man acted alone.
He said that rage and “psychological instability” are often factors in such cases, but added that he wouldn’t speculate on whether that was the case here.
Police chief Rene Demmler said the man drove from the Augustusplatz, a major square, along the Grimmaische Strasse into the city’s central pedestrianised shopping area. He stressed that there was no longer any danger.
Mr Demmer said the driver was arrested in the vehicle and didn’t resist arrest.
Photos from the scene showed a car with a battered front and a shattered windshield after the incident, which happened at about 5pm.
Leipzig is located southwest of Berlin and has more than 630,000 inhabitants, making it one of the biggest cities in eastern Germany.