The shooting at a Fourth of July parade in Highland Park that left at least six dead and 24 wounded, has rocked the small, well-off community in suburban Chicago, but also shocked America as a whole.
It is merely the latest in a slew of mass killings in the US that have recently included a shooting at a school in Texas and the racist massacre of Black shoppers at a super market in Buffalo, New York.
But this latest mass murder has struck a particularly symbolic note as the shooter targeted a flag-waving parade celebrating the country's national day and - once again - forced Americans to wrestle with how and why their nation is so often struck by such bloody attacks.
Highland Park's mayor, Nancy Rotering, said: "This morning at 10:14, our community was terrorized by an act of violence that has shaken us to our core. Our hearts go out to the victims at this devastating time. 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 up on us."
Video capturing the parade showed members of a marching band fleeing as gunshots were heard nearby. The suspect, described as a white male with dark hair in his late teens or 20s, still has not been found.
Highland Park police commander Chris O'Neil called the shooting a "horrific, senseless, random act of violence".
Giffords Courage, the gun control advocacy organization led by former congresswoman Gabby Giffords, who was shot at a public event in Tuscon, Arizona, in 2011, responded to the shooting in Illinois: "A mass shooting caused people to run for their lives at a Fourth of July parade in Highland Park, IL. Multiple people are reported dead or injured. This is not normal. We should be able to live free of the fear of being shot."
Shannon Watts, founder of gun reform group Mom's Demand, said: "Media reporting the gunman - a white teen or young man - had a rifle and was in a 'sniper position' on a rooftop as he picked off people below at the Highland Park parade. This isn't freedom; it's terrorism."
US singer and 80s pop-rock icon Richard Marx, who is from Highland Park, tweeted: "My heart is always broken by these constant mass shootings no matter where they occur but today I'm extra heartbroken. And extra angry at the senselessness."
Local politicians also weighed in and vowed to take action to end gun violence in the US - though such sentiments are often expressed in the wake of these tragedies and there is rarely any meaningful progress towards gun reform.
The Illinois governor, JB Pritzker, said: "Grief will not bring the victims back and prayers alone will not put a stop to the terror of rampant gun violence in our country … we must and we will end this plague of gun violence."
Meanwhile, shortly before the tragedy, the National Rifle Association gun lobby group shared a message on Twitter in honor of Independence Day: "We are a country because of brave souls with guns who valued and fought for liberty and freedom."
A bald eagle was pictured in the video associated with the tweet, along with a voiceover: "The only reason you're celebrating Independence Day is because citizens were armed. Happy Fourth of July from the National Rifle Association of America."