A gunman perched on a rooftop opened fire on families waving flags and children riding bikes at a Fourth of July parade on Monday, killing six and wounding more than 36 in the Chicago suburb of Highland Park.

The gunman climbed to the roof of a business using a ladder in an alley, police said. The attack turned a civic display of patriotism into a scene of panicked mayhem.

Hours later, police announced that they had a suspect in custody after 22-year-old Robert E. Crimo III surrendered to authorities.

The main street in Highland Park is now a crime scene spanning blocks, strewn with abandoned chairs and flags. Witnesses came back to retrieve strollers and other items later on Monday but were told they could not go beyond the police tape.

"It sounded like fireworks going off," said retired doctor Richard Kaufman who was standing across the street from where the gunman opened fire, adding that he heard about 200 shots.

"It was pandemonium," he said. "People were covered in blood tripping over each other.”

The shooting comes with gun violence fresh on the minds of many Americans.

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A gunman on May 24 murdered 19 school children and two teachers at an elementary school in Uvalde, Texas, just 10 days after a man shot dead 10 people at a grocery store in Buffalo, New York.

The latest attack is likely to rekindle the debate about gun control and whether stricter measures can prevent mass shootings that happen so frequently in the United States.

Police said they did not know what the motive was for the shooting in Highland Park on Monday. Those wounded ranged in age from 8 to 85, including four or five children.

The New York Times named one of the dead as 76-year-old Nicolas Toledo, who was in a wheelchair and had not wanted to attend the parade, but his disabilities required that he be around someone full time and his family had not wanted to miss the event.

"We were all in shock,” his granddaughter Xochil Toledo said. "We thought it was part of the parade."

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At least one of those killed was a Mexican national, a senior Mexican foreign ministry official said on Twitter.

Violent Images Online
Social media and other online posts written by accounts that appeared to be associated with either Crimo or his rapper alias, Awake The Rapper, often depicted violent images or messages.

The accounts showed a man with physical characteristics and facial tattoos similar to those in photos of the suspect released by police.

One music video posted to YouTube under the Awake The Rapper name, for example, showed drawings of a stick figure holding a rifle in front of another figure spread on the ground.

In a different video, a stick figure is shown bleeding in front of police cars. Reuters could not verify if the YouTube account belonged to Crimo, although the account was terminated on Monday after he was named a suspect.

A YouTube spokesperson did not respond to a request for comment.

President Joe Biden said he and his wife Jill were "shocked by the senseless gun violence that has yet again brought grief to an American community on this Independence Day."

Biden referred in his statement to bipartisan gun-reform legislation he signed recently but said much more needed to be done, and added: "I’m not going to give up fighting the epidemic of gun violence."

'Really Traumatising'
A 36-year-old native of Highland Park who wanted to be identified only as Sara, told Reuters she had attended the annual parade most years since her childhood.

"Not even five minutes after, very shortly after, the police and firetrucks part of the parade had gone by I heard ‘pop, pop, pop, pop, pop,’" she said, adding that she first thought they were muskets sometimes used in parades.

"The popping didn’t stop ... again it went ‘pop, pop, pop, pop, pop’ and I turned and I said ‘those are gun shots, run!’”

Highland Park's population is 30,000 and nearly 90% white, according to the US Census Bureau. About a third of the population is Jewish, according to the Jewish Telegraphic Agency.

After the Uvalde and Buffalo shootings, Congress last month passed its first major federal gun reform in three decades, providing federal funding to states that administer "red flag" laws intended to remove guns from people deemed dangerous.

The law does not ban sales of assault-style rifles or high-capacity magazines but does take some steps on background checks by allowing access to information on significant crimes committed by juveniles.