At least six people were killed in a mass shooting at a Fourth of July parade in the affluent community of Highland Park, Illinois, just 20 miles north of Chicago, according to local officials

 The Chicago Sun-Times reported that the parade began on Monday around 10 a.m. but it was suddenly halted 10 minutes later after shots were fired. Robert “Bobby” E. Crimo III, a “person of interest” in the shooting, was later taken into custody. According to NBC News, Crimo “left a long trail of tributes to mass shootings and public killings on social media platforms.”

Lake County Major Crime Task Force spokesman Christopher Covelli said at a news conference that the gunman opened fire on parade-goers from a rooftop using a “high-powered rifle” that was recovered at the scene. He didn’t know which building, according to WGN News.

One witness, Miles Zaremski, told CNN said he heard what he believed to be 20-25 gunshots. He said it was an AR-15-style weapon and saw at least one person bloodied and on the ground. “I was sickened,” said Zaremski.

“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.

Rep. Brad Schneider (D-Ill.) was scheduled to walk in the parade and confirmed the shooting in a post on Twitter and the apparent loss of life. 

“My campaign team and I were gathering at the start of the parade when the shooting started. My team and I are safe and secure,” he said.

Like many small towns across the U.S., the annual parade in Highland Park was meant to celebrate Independence Day and community. Instead, it’s now yet another numbing statistic in the seemingly relentless attacks against fellow Americans involving a high-caliber rifle as hundreds of attendees ran for their lives, leaving behind clothing, food, and chairs.

Illinois Gov. J.B. Pritzker said in a statement: “There are no words for the kind of monster who lies in wait and fires into a crowd of families with children celebrating a holiday with their community.” He added, “We must — and we will — end this plague of gun violence.”

Debbie Glickman, a Highland Park resident, said that she was on a parade float with coworkers and the group was prepared to turn onto the main route when she saw people running away from the area.

“People started saying ‘There’s a shooter, there’s a shooter, there a shooter,'” Glickman told the Associated Press. “So we just ran. We just ran. It’s like mass chaos down there.”

The attack in Highland Park is the most deadly incident following recent massacres, including an 18-year-old gunman who killed 19 children and two adults at a school in Uvalde, Texas, on May 24. Just ten days prior, a racist attack led to the deaths of 10 Black people at a supermarket in Buffalo, New York.

This article was updated as information became available.