CHICAGO (NewsNation) — On a day meant for celebration, the nation is mourning at least six people who were killed in a mass shooting at a July 4 parade in Highland Park, Illinois, on Monday morning.

“On a day that we came together to celebrate community and freedom, we are instead mourning the tragic loss of life and struggling with the terror that was brought upon us,” Highland Park Mayor Nancy Rotering said.

About two dozen people ranging from age 8-85 were also injured in the shooting and Highland Park Hospital officials said at least “four or five” of those injured were children. Five people who died at the scene were all adults and a sixth person died at a hospital, though that victim’s age is unknown.

An hourslong manhunt is underway for the suspect. A 21-year-old Highland Park man was named a person of interest in the shooting.

“Jill and I are shocked by the senseless gun violence that has yet again brought grief to an American community on this Independence Day,” President Joe Biden said in a statement. “As always, we are grateful for the first responders and law enforcement on the scene.”

Biden also committed federal law enforcement officers to assist in the investigation and manhunt.

Illinois Gov. JB Pritzker took to Twitter on Monday, calling for “all Illinoisans to pray for the families who have been devastated by the evil unleashed this morning in Highland Park.”

Pritzker also held a news conference Monday, first thanking first responders for saving lives, then to the residents of Highland Park, telling them, emphatically, that the “murderer will be brought to justice” and that every resource at the states disposal will be available.

“There are no words I can offer to lessen the pain of those families who will no longer associate the Fourth of July with celebration, but instead with grief. Please know that our state grieves with you,” he continued.

The Chicago White Sox said in a statement that they would hold a moment of silence for the victims of the shooting ahead of Monday evening’s game against Minnesota. They also plan to cancel the postgame fireworks.

“The entire Chicago White Sox organization expresses our deepest sympathies to the families and friends of the innocent victims of today’s horrific shooting and all of those who have been affected by this tragedy.”