A nine-week-old girl and her father were among five people killed when a car drove at speed into pedestrians in the German city of Trier.
It happened at around 1.45pm on Tuesday in a pedestrianised area of the southwestern city, around 120 miles (193km) from Frankfurt.
Police said 15 people had also been injured - with some described as having the "most severe injuries".
The state's interior minister said the driver had apparently targeted people by zig-zagging across the street for about 900m.
The 51-year-old driver, who was born in Trier, was arrested and a silver Land Rover seized.
Police said there was currently no evidence of a political or religious motive, while a prosecutor said the suspect was drunk and may have had a mental illness.
The baby was at first said to be nine months old, before police corrected themselves and said she was just nine and a half weeks.
Her father, 45, was also killed, as were three women - 25, 52 and 73. All of them were from Trier.
Of those injured, four are said to be in a life-threatening condition, while five are seriously hurt and six suffered less severe injuries, state interior minister Roger Lewentz said.
Watch: 'Several dead' as car drives into pedestrians
The city's Mayor Leibe told broadcaster SWR shortly after the attack: "We have a driver who ran amok in the city...
"I just walked through the city centre and it was just horrible. There is a trainer lying on the ground, and the girl it belongs to is dead."
The mayor, who was brought to tears as he talked about the scene of the incident, added: "I can't understand how someone gets the idea to drive through the city centre with an SUV to kill people.
"Kill people - a baby, nine months old, to a woman 72 years old; what did these people do? They just wanted to go to the city, shop, and now they are dead."
An eyewitness told Trierischer Volksfreund that the car had driven from the city's Roman gate - the Porta Nigra - along a shopping street towards the main market and then on to Fleischstrasse, where it hit several pedestrians.
Another person told the newspaper they saw a pram fly through the air at the market, before passers-by flooded into her shop trying to escape.
Police were able to stop the car in nearby Christophstrasse, the witness said.
A video on social media shows police pinning a man to the ground next to a damaged silver car.
Prosecutor Peter Fritzen said the suspect had no fixed address and had recently been living in the Land Rover - which was borrowed from a friend.
He said a doctor had recently reached the preliminary conclusion that the suspect may have been suffering a mental illness.
Trier - the birthplace of Karl Marx - is on the border with Luxembourg and has a population of about 110,000.
It is four years since a terrorist drove a truck through a Christmas market in Berlin, killing 12 people.