BERLIN - A car has driven into a crowd of people in the western German city of Mannheim, causing casualties, the Mannheimer Morgen newspaper reported on Monday, citing witnesses.

Local police said a police operation was under way in the city center, without giving further details.

The incident occurred as crowds gathered in cities across regions including Germany's Rhineland for parades to mark the carnival season.

READ MORE: Suspect arrested after two killed in knife attack in German park

A black SUV drove at high speed into people, travelling from the centrally located Paradeplatz square towards the city's landmark water tower, the Mannheim24 news website reported, adding that several people were severely injured.

Security has been a key concern in Germany following a string of violent attacks in recent weeks, including deadly car rammings in Magdeburg in December and in Munich last month, as well as a stabbing in Mannheim in May 2024.

READ MORE: Memorial service held for victims in German Christmas market attack

Police were on high alert for this year's carnival parades after social media accounts connected to the Islamic State militant group called for attacks on the events in Cologne and Nuremberg.