Driver to be charged with "intentional homicide" after killing 5 in Christmas parade
Police believe the suspect was involved in a domestic dispute shortly before the incident.
An SUV struck paraders during the annual Christmas parade in the Milwaukee suburb of Waukesha on Sunday night.
The suspect has since been identified by police as 39-year-old Darrell Brooks.
Police Chief Dan Thompson has also identified those killed as four women aged 52-79 and an 81-year-old man.
"We are confident he acted alone," said Chief Thompson. "There is no evidence that this was a terrorist incident."
He added that there was no reason to believe the suspect knew anyone in the parade.
Investigators had been looking into whether the SUV driver had been fleeing from a crime and found that he was likely involved in a domestic dispute shortly before the incident took place.
Chief Thompson said police were not pursuing Brooks when he entered the parade but an officer fired shots at the car in an attempt to stop it. They do not believe shots had been fired from the vehicle, despite earlier reports.
Videos captured by onlookers and a livestream show the moment a red SUV ploughed into the crowd, appearing to run over at least a dozen people.
The city of Waukesha later confirmed the fatalities in a tweet, warning that the number could change.
The Children's Wisconsin hospital officials said they treated 18 children, including six who remained in critical condition and three in serious condition on Monday.
Attorney General for the Wisconsin Department of Justice Josh Kaul previously described the event as a "devastating incident".
Witness Angela O'Boyle, who watched events unfold from her apartment window overlooking the parade, told CNN: "All I heard was screaming and then people yelling out their children's names."
Survivor Corey Month told the Milwaukee Journal Sentinel: "There were pompoms and shoes and spilled hot chocolate everywhere. I had to go from one crumpled body to the other to find my daughter.
“My wife and two daughters were almost hit. Please pray for everybody. Please pray.”