On Sunday night in Waukesha, Wisconsin, there was going to be a party. The Milwaukee suburb's Christmas parade, returning from a pandemic hiatus, featured dance groups, high school bands, and politicians walking down Main Street.

Then, in a terrifying image filmed on the city's livestream and by witnesses' cellphones, an SUV driver raced through a police line and into a procession of Christmas marchers, hitting more than 20 adults and children.

Authorities said they didn't have quick information on the seriousness of the injuries. Although "some" fatalities were recorded, authorities declined to publish the names of those who died, citing the victims' families' right to privacy.

Children's Hospital of Wisconsin stated it had received 15 patients from the incident at 8 p.m., with no fatalities recorded.

According to a statement, Aurora Medical Center in Summit was treating a total of 13 patients late Sunday, with three in critical condition, four in serious condition, and six in fair condition.

That red SUV has been found, and the person of interest is in custody, authorities said.  The investigation was still underway.

A Waukesha police officer fired his gun in an attempt to stop the SUV as it crashed through barricades, Waukesha Police Chief Dan Thompson said. No onlookers were hurt, and Thompson said he didn't know if the officer's bullets hit the driver.

One video captures the moment the SUV smashed past the barricades, as well as the sound of many gunshots. A group of individuals tends to one of the girls who are on the ground in the video shot after the pompom dancers were struck.

"Today, our town saw horror and sadness in what should have been a communal celebration," Mayor Shawn Reilly said, recalling seeing joyful children and happy parents as he marched down the parade route before the shooting.

"I'm profoundly disappointed to learn that so many members of our community attended a parade only to suffer harm and heartbreak," the mayor said.

The motorist was described as male by eyewitnesses, however, the police did not confirm this.

"Then there was a loud blast... and then there were deafening yells and screams from the crowd, from the paradegoers... And people started rushing, sprinting away, screaming with tears in their eyes," Angelito Tenorio, a West Allis alderman running for Wisconsin state treasurer, told The Associated Press.

This was Waukesha's 58th Christmas parade, an annual event that was canceled because of the pandemic last year. The event's theme this year was simply "Comfort and Joy."