Christmas parade: SUV mows down crowd, several killed, person of interest in custody: LIVE UPDATES

“The White House is closely monitoring the situation in Waukesha and our hearts go out to everyone who has been impacted by this terrible incident," the Biden White House said in a statement. "We have reached out to state and local officials to offer any support and assistance as needed.”

A Wisconsin man attending the Waukesha Christmas parade said the red SUV that slammed into participants Sunday struck at least 10 people as he was stepping out of a pub along the parade route.

“As I was opening the door to walk out, people started yelling and running in -- and that's when I saw the red SUV,” Jordan Woynilko, a Milwaukee man who shared video of the incident’s aftermath under his Twitter handle, @J_Woynilko, told Fox News Digital Sunday evening. “I saw it drive through and hit the people.”

He said he grabbed his friend, and they were both in shock as they made their way through the carnage. Good Samaritans were attempting CPR on multiple victims before paramedics arrived, he said.

“It was horrific as we were walking, and then when we turned off the main street there to walk up a few more blocks to the car, there were cops peeling around the corner, we’re assuming looking for the guy.”

"There were moms and dads yelling for their kids, people running around," Woynilko added. "When I rewatched the video, I could hear people talking, and they were like, 'There's eight people injured down there. We need an Ambulance over here.' There's one lady kneeling on the ground crying."

Fox News' Michael Ruiz contributed to this report

"The FBI Milwaukee field office is aware of the reporting of an incident in Waukesha," an FBI spokesperson told Fox News Digital. "The local and state authorities are leading the response."

Brayden Kowalski, a 19-year-old man who grew up in Waukesha, said that he was at the parade with his family when he saw an SUV accelerate through the crowd. 

"He’s just blowing through people, kind of just dinging a lot of people, bodies flying everywhere,” Kowalski said. "These people didn’t get run over, they got f------ thrown through the air. Like a lot of people got tossed up into the air.”

Almost immediately after the SUV went through the crowd, Kowalski and his mom went out into the crowd to try to help people who were hurt. "You could see the fragments of brains,” he said. "There were quite a few people with broken limbs, like a lot of broken legs, a lot of people shouting with broken legs. It was horrifying.”

Kowalski grew up in Waukesha, a town of about 70,000 people. "This is the most peaceful loving town. Everyone is so friendly,” Kowalski said. "I know people say, ‘You would never expect this to happen here.' But this is one of those towns. You would have never thought this would happen."

Kowalski also said that he heard three shots fired after the car plowed through the parade.

Fox News' Paul Best contributed to this report

Fox News correspondent Mike Tobin reports from Waukesha, Wisconsin to discuss the latest on a vehicle that drove through Christmas parade.

"Kathy and I are praying for Waukesha tonight and all the kids, families, and community members affected by this senseless act," Governor Tony Evers tweeted Sunday. "I'm grateful for the first responders and folks who acted quickly to help, and we are in contact with local partners as we await more information."

A mother recounts the scene of a car driving through a holiday parade in Waukesha, Wisconsin on ‘Sunday Night in America.’

Eyewitness Jeff Wierzelewski discusses what he saw on 'Fox Report' after reports a red SUV crashed into a parade in Waukesha, Wisconsin.