Hundreds of people took over a major Chicago highway, shutting down all northbound lanes of traffic on the Interstate 94 - the Dan Ryan Expressway - to protest against gun violence in the city.
The "Dan Ryan Shut Down," as it was billed, was organised by ChicagoStrong, a group of students advocating to reduce gun-related deaths.
"Too many people are shot and killed in our city each week, but our stories never gain national attention. We need America to hear our voices too because Chicago's problems are America's problems," the group states on its website. "We're going to disrupt the flow of traffic July 7th to make sure they know we're serious."
They were serious.
At around 10am local time, the marchers started at 79th Street and Dan Ryan, near an "L" stop on the south side the city, and began moving north on the highway en masse.
Earlier, Illinois State Police had released a statement saying protesters were allowed to occupy all but two northbound lanes of the Dan Ryan Expressway and that police and transportation authorities would be "providing a safety barrier between the motoring public travelling on the interstate and the marchers."
However, the protesters - led by the Rev Michael Pfleger, a prominent activist and Catholic priest in Chicago, as well as the Rev Jesse Jackson - soon faced a standoff with police, demanding access to the entire highway, the Chicago Tribune reported.
Pfleger would later tell the newspaper that they had given police three weeks' advance notice and that they had had permission to occupy all of the lanes.
Eventually, police agreed that the march could take place in the northbound lanes, effectively shutting down the expressway towards downtown Chicago for about an hour, the newspaper reported.
On social media, Jackson said they were marching to draw attention to the growing disparity between what he called three different Chicagos. The south and west sides of the city, he said, faced "growing desperation" because they need jobs, education, infrastructure and justice.
"This is why we are peacefully marching today," Jackson tweeted.
"We came out here to do one thing: to shut it down," said Pfleger, dressed in a clerical collar and a shirt that depicted raised fists and the words "Enough is Enough: Peace Now!!" according to the Tribune. "We came here to get their attention. Hopefully we got their attention. . . . Today was the attention-getter, but now comes the action."
Representatives for ChicagoStrong did not immediately respond to a request for comment or queries about how large the crowd was. However, images of the march showed protesters blanketing the expressway, filling up overpasses, raising their arms, shouting and waving bright signs that read "Can you hear us NOW?" and "STOP THIS SENSELESS VIOLENCE."
At one point, Pfleger was seen marching arm-in-arm with Chicago Police Superintendent Eddie Johnson, according to Chicago Sun Times reporter Ashlee Rezin.
The protest seemed to attract the attention of the National Rifle Association, which tweeted a video featuring NRA spokeswoman Dana Loesch deriding similar demonstrations, saying such protesters set out to "smash windows, burn cars, shut down interstate and airports, bully and terrorise the law abiding - until the only option left is for police to do their jobs."
The NRA's tweet was met with befuddled responses pointing out Chicago's "Dan Ryan Shut Down" had been a "fully peaceful protest."
The massive protest also attracted several prominent supporters, including former Parkland students David and Lauren Hogg, and former education secretary (and Chicago native) Arne Duncan.