The victims included Virginia Sorenson, 79, the group’s choreographer; Leanna Owen, 71, a dancer; and Tamara Durand, 52, a new member performing for the first time. Also killed were a dancer’s husband, Wilhelm Hospel, 81, and Jane Kulich, 52, a Citizens Bank teller.
The motive for the attack is unclear.
Chief Thompson said Mr. Brooks intentionally struck people with his car after fleeing a domestic dispute possibly involving a knife. Police officers were responding, though not pursuing Mr. Brooks, when he veered into the parade route, officials said.
Chief Thompson said there was no indication that Mr. Brooks knew anyone marching in the parade, nor was there any sign that the incident was an act of terrorism.
The suspect had recently been released from jail.
Mr. Brooks had been arrested repeatedly in Wisconsin since the 1990s, accused at different points of battery and domestic abuse and resisting the police. This month, prosecutors in Milwaukee said, he intentionally ran over a woman he knew with a maroon Ford Escape. Prosecutors in Milwaukee County said they had erred in recommending a $1,000 cash bail in that case.
The attack marred a beloved holiday tradition.
Mayor Shawn Reilly described the march down Main Street as “a Norman Rockwell type of Christmas parade” that has been a cherished event in Waukesha for decades, with high school bands and dance troupes and local politicians all walking through town. Residents were especially excited for this year’s iteration after the parade was called off in 2020 because of Covid-19. More than 60 entries, from the Fire Department to the Waukesha Old Car Club to Santa Claus, had signed up for the parade.
“That parade became a nightmare,” Mr. Reilly said on Monday. “Lives were lost during the middle of what should have been a celebration.”
It is unknown why Mr. Brooks was in Waukesha.
Chief Thompson said Mr. Brooks had been involved in a domestic dispute shortly before he drove through the parade. But the police did not respond to questions about exactly where that dispute took place, or why they believe that Mr. Brooks had come to Waukesha in the first place. In court records, Mr. Brooks usually listed addresses in Milwaukee, about 20 miles east of Waukesha.
Giulia Heyward contributed reporting.