A video posted on social media shows a red SUV entering the show from behind. Onlookers scream as the car crashes into the first people. In a second video, police appear to open fire on the same vehicle as it breaks through the barrier. A police spokesman confirmed that an officer fired on the car.

The accident occurred during a Christmas parade in Waukesha near Milwaukee. Police urged residents to avoid the city centre. It is not yet clear whether this was an accident or an attack. The police said during a press conference, that the police managed to track down the involved car and have now arrested the driver. There is no clear motive yet.

According to the head of the local fire service, 11 adults and 12 children were taken to different hospitals. Children’s Hospital of Wisconsin told the AP that it has admitted 15 children, but has not yet reported any deaths among them.

Other hospitals in the area reported treating 28 patients in connection with the impingement. Reports said three of them are in critical condition CNN.

A witness, Angelito Tenorio, told the Associated Press that he was watching the show with his family when they saw the car approaching. “We heard a loud bang and then all we heard was a deafening scream. We saw people crying as they ran away. It happened so fast, it was so terrifying.”

“What happened in Waukesha today is disgusting,” Wisconsin Attorney General Josh Cowell wrote on Twitter. I am confident that those responsible will be brought to justice.”

Waukesha celebrates its 125th anniversary this year with different festivities spread throughout the year. The parade traditionally begins the winter season in suburban Milwaukee.