People light candles at the Porta Nigra for the victims after a car drove into pedestrians in Trier, southwestern Germany on Tuesday. Photo: AFP

A baby was among five people killed when a car tore through a pedestrian shopping street in the southwestern German city of Trier on Tuesday, police said, after arresting the driver.

Prosecutor Peter Fritzen said the driver, a 51-year-old Trier native, appeared to be suffering from "psychiatric problems" and had been under the influence of alcohol during the incident.

Police said they had "no indications of a political motive" after questioning the suspect, and Fritzen said prosecutors were considering requesting he be placed in psychiatric care.

At the same press conference, Trier Mayor Wolfram Leibe said those killed when the man drove his SUV into the shoppers included a nine-month-old and a 73-year-old woman. 

"I think this is Trier's darkest day since World War II," he said.

Also killed were a 25-year-old woman and a 45-year-old man. Police have not yet released details on the fifth victim. 

Malu Dreyer, premier of the state of Rhineland-Palatinate where Trier is located, expressed shock that a baby was among those killed by the driver's "insane act" and shared her condolences with all the affected families.

The baby's mother was being treated in hospital for injuries sustained in the rampage.

The incident started around 1250 GMT and ended within four minutes of the first emergency calls arriving, with police intercepting the driver after he turned off a main shopping street.

AFP