Police in Highland Park, near Chicago have arrested and detained Robert E Crimo III after a brief chase after shooting dead six people at an Independence Day parade from a rooftop.
The parade was suddenly halted shortly after 10:00 local time (15:00 GMT), when several shots were heard.
The suspect, Robert E Crimo III, is said to have targeted the parade at random with a high-powered rifle.
The 22 year old gunman opened fire at the parade at around 10:15 local time, just a few minutes after it started.
The event was scheduled to include floats, marching bands, and community entertainment as part of the city’s Independence Day celebrations.
But what should have been one of the happiest days of the year quickly turned to panic, with pushchairs, purses and lawn chairs left discarded on the street as people fled in all directions.
The suspect is believed to have fired at members of the public from the rooftop of a nearby shop, where police say they recovered “evidence of a firearm.”
Five adults were killed at the scene, as well as a further victim who the local coroner said died in a nearby hospital. Twenty-four people were also hospitalized.
The Fourth of July is a national holiday marking the date the American colonies declared independence from Great Britain in 1776.
The shooting comes just a month after the deadly shootings in Uvalde, Texas and Buffalo, New York – and a week after the US Congress passed bipartisan legislation on gun control in America.