Police are searching for a rooftop gunman who shot dead six people at an Independence Day parade near the US city of Chicago.
The event in the city of Highland Park, Illinois, was suddenly halted shortly after 10:00 local time (15:00 GMT), when several shots were heard.
Twenty-four people were taken to hospital, officials say.
A suspect has been named as Robert E Crimo III, 22. Police said he is considered armed and dangerous.
Police said the suspect appeared to have targeted the parade’s attendees at random with a high-powered rifle.
The suspected gunman opened fire at the parade at around 10:15 local time, just a few minutes after it began.
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 crowds fled from the scene.
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.
“On a day that we came together to celebrate community and freedom, we’re instead mourning the tragic loss of life,” said city mayor Nancy Rotering.
The Fourth of July is a national holiday marking the date the American colonies declared independence from Great Britain in 1776.