Two people were killed after a driver rammed his car into the crowd in Germany's Leipzig city on Monday, according to authorities.
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 René Demmler said the man drove from the Augustusplatz, a major square, along the Grimmaische Strasse into the city's central pedestrianized shopping area. He stressed that there was no longer any danger.
The driver was arrested in the vehicle and didn't resist arrest, Demmler said.
Saxony state Gov. Michael Kretschmer expressed his condolences to the families of the victims.
"An act like this leaves us speechless - and it makes us determined," he added, according to German news agency dpa. "We will do everything in our power to solve this case quickly and completely.”
Photos from the scene showed a car with a battered front and a shattered windshield after the incident, which happened at about 5 p.m.
Leipzig is located southwest of Berlin and has more than 630,000 inhabitants, making it one of the biggest cities in eastern Germany.
