Seven people have died and dozens were seriously injured in relation to the shooting at a Fourth of July parade in Highland Park, Illinois, police confirmed via ABC News.
Local residents in the downtown Highland Park area are urged to shelter in place as the suspect remains at large.
The suspect is described as a man between the ages of 18 and 20 and is believed to have fired shots from a roof in what police described as a "random act of violence."
City officials also confirmed a rifle was recovered in relation to the incident, but warned that the suspected shooter should still be considered armed and dangerous.
The FBI said it has sent resources to the scene of the shooting.
Local police are responding to a reported shooting incident in Highland Park, a suburb of Chicago, that took place during a Fourth of July parade, Highland Park Mayor Nancy Rotering announced on her verified Twitter account Monday (July 4).
"Highland Park Police are responding to an incident in downtown Highland Park," Rotering tweeted. "Fourth Fest has been canceled. Please avoid downtown Highland Park. More information will be shared as it becomes available."
Illinois Governor JB Pritzker also tweeted a response to the shooting, confirming that his staff was "closely monitoring the situation" and that "State police are on the scene and we have made all state resources available to the community.
Rep. Brad Schneider (D-Ill.) attended Monday's parade and provided additional details on his verified Twitter account.
"Today a shooter struck in Highland Park during the Independence Day parade," Schneider tweeted. "My campaign team and I were gathering at the start of the parade when shooting started. My team and I are safe and secure. We are monitoring the situation closely and in touch with the Mayor.
"Hearing of loss of life and others injured. My condolences to the family and loved ones; my prayers for the injured and for my community; and my commitment to do everything I can to make our children, our towns, our nation safer. Enough is enough!"
Evanston, Illinois, a neighboring suburb, canceled its 4th of July parade amid news of the shooting in Highland Park, the Evanston Police Department announced on its Twitter account Monday afternoon.
"While there is no known threat to Evanston residents, the shooter is still at large; and cancelations are taking place in an abundance of caution," the department tweeted. "Our thoughts and prayers go out to our neighbors to the the north."
THIS IS A DEVELOPING STORY AND WILL BE UPDATED.