WAUKESHA, Wisc. (CBS Chicago) — Five people were killed and more than 40 people were injured during the Waukesha Holiday Parade after a vehicle plowed into the parade route Sunday, police confirm.

Among those injured were at least 12 were children.

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Waukesha Police Chief Dan Thompson said there is a person of interest in custody. He added there are no other threats in the area.

Police say the driver of the vehicle drove through barricades and into the parade.

Graphic video posted online shows a red SUV drive into the parade, striking a number of people as they marched in the parade. Others can be seen running away and screaming as the SUV continued on while others run to the aid of victims lying in the road.

“Today we experienced a horrible senseless tragedy,” said Waukesha  Mayor Shawn Reilly. “My heart goes out to all those affected by this senseless act. “

Photos posted by CBS 58 show what appears to be the red SUV parked outside a home after the incident.

The police chief confirmed a “suspect vehicle” was recovered.

Another video posted on Twitter showed a number of small groupings on the street providing aid to injured individuals lying on the ground.

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Thompson said some of those injured were taken by police to hospitals, and others were taken by family members.

Police in Waukesha are urging people to avoid the downtown area. CBS 2’s Marissa Parra noted a number of streets blocked off in the area in the aftermath. Thompson said roads will remain closed in the area for 24 hours.

Witnesses originally reported hearing shots fired during the incident. Police now confirm those shots came from an officer. They do not believe anyone inside the vehicle fired any shots and say no bystanders were injured.

Thompson said the officer who fired his weapon has been with the department for 6.5 years.

A witness who was at the parade described the scene, saying many of those injured were in parade costumes.

“I could see kids on the ground, little bodies on the street. I’m still in shock.”

School is canceled Monday for the School District of Waukesha for all students in grades 4K to 12, according to a letter sent out by the district superintendent. There will also be additional counselors available during the school day at all buildings for students who need support.

A decision will be made regarding Tuesday during the day on Monday, the letter said.

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The Archdiocese of Milwaukee addressed the tragedy with the following statement:

Our prayers are with the people who have been injured and killed during the tragic incident in Waukesha.

Among the injured are one of our Catholic priests, as well as multiple parishioners and Waukesha Catholic school children.

Please join us in prayer for all those involved, their families, and those who are traumatized from witnessing the horrible scene.

Police plan to release additional updates at a news conference at 1 p.m. (CT) on Monday.

Waukesha is located just west of Milwaukee.