A rooftop shooter killed at least six people and wounded 24 more at a July Fourth parade in an affluent Chicago suburb on Monday, authorities said.

Also, a man arrested on suspicion of killing three people and wounding several others during a shooting at a shopping mall in Copenhagen on Sunday had been remanded in a psychiatric facility for 24 days, Danish police said yesterday.

For the Illinois killings, a rifle had been found and police are searching for a gunman who opened fire at Highland Park police, Commander Chris O’Neill told reporters.

According to NBC News, the city of Highland Park confirmed that there’s “an active shooter incident” and urged all, “individuals are advised to shelter in place.”

“Law enforcement agencies are searching for the suspect; evidence of a firearm has been recovered,” the city said. “Numerous law enforcement officers are responding and have secured a perimeter around downtown Highland Park.”

The shooting happened “in the area of the Independence Day parade route,” the Lake County Sheriff’s Office said in a statement posted to Twitter.

Illinois State Police also responded to the scene, “assisting Highland Park PD with an active shoot situation,” according to a statement the agency tweeted.

Police were spotted scouring rooftops around Central Avenue near Green Bay Road and Second Street in the aftermath of gunfire.

“It does appear that he was shooting from a roof,” Lake County Sheriff’s Deputy Chief Christopher Covelli told reporters.

Fourth of July events in other Chicago suburbs, Evanston and Skokie, were also called off in the wake of the Highland Park shooting.

“Unfortunately as you may know, we have an active shooter situation in Highland Park at their parade,” Illinois Gov. J.B. Pritzker told reporters at the Independence Day event in nearby Evanston.

“I’m still getting reports.”

United States Rep, Brad Schneider was at the Highland Park event when shots rang out.

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

Witness Larry Bloom said at first people thought the popping sound was part of the parade.

“You heard like a ‘pop, pop, pop,’ and I think everybody kinda thought maybe it was a display on one of the floats and then it just opened up,” he told NBC Chicago.

“I was screaming and people were screaming,” Bloom added. “They were panicking and and they were just scattering and I, you know, we didn’t know. You know, it was right on top of us.”

Suspect in Fatal Copenhagen Mall Shooting Remanded in Psychiatric Facility for 24 Days

Meanwhile, a man arrested on suspicion of killing three people and wounding several others during a shooting at a shopping mall in Copenhagen is being remanded in a psychiatric facility for 24 days, Danish police said yesterday.

The 22-year-old Danish man was known to psychiatric professionals, CNN quoted to have police said earlier.

The suspect was charged with manslaughter, Copenhagen Police tweeted. The court who heard the case yesterday, put a ban on naming both the suspect and 10 victims named in the charge, the force added in a series of tweets.

The shooting unfolded on Sunday at multiple locations inside Field’s, a shopping center in the Danish capital. Social media footage showed people running through the mall and heavily armed law enforcement officers on the scene.

At a press conference, Copenhagen’s Head of Police Soren Thomassen said two 17-year-old Danish citizens, one male and one female, and a 47-year-old Russian national had been killed in the gunfire.

Two other Danes and two Swedish nationals had received gunshot wounds and were in hospital in critical but stable condition, while several others sustained minor injuries while leaving the mall, Thomassen said.

The man arrested in connection with the shooting is currently the only suspect. Thomassen said there was no indication the suspect was acting with others but an investigation was ongoing.

Earlier, the police had said they detained the suspect 13 minutes after receiving the first emergency call, and that he was “carrying a rifle and ammunition” at the time of his arrest.

At the news conference, Thomassen said there was no indication the attack was an “act of terror” nor motivated by gender, and police believe the victims were chosen at random. The suspect was “known to people in the psychiatric field,” he said.

Gun violence is relatively rare in Denmark. Copenhagen’s last major shooting incident was in 2015, when a gunman attacked a free speech forum featuring controversial cartoonist Lars Vilks, killing one man and wounding three others.

As investigators piece together the circumstances that lead to Sunday’s deadly shooting, questions are being asked as to how the suspected gunman could have obtained the weapon and ammunition used in the attack, as Denmark is considered to have some of the most restrictive gun laws in Europe.

Whereas in the United States gun ownership is conditionally guaranteed by the US Constitution, in Denmark, the right to private gun ownership is not guaranteed by law, according to GunPolicy.org, an organisation that tracks international firearm policy.

Through restrictive licensing, Danish authorities attempt to reduce firearm violence by substantially reducing the number of firearms in circulation. An applicant for a firearm license in Denmark must pass a background check which considers criminal and mental health, GunPolicy.org said.

Only licensed gun owners may lawfully acquire, possess or transfer a firearm or ammunition. Applicants for a gun owner’s license in Denmark are required to establish a genuine reason to possess a firearm, for example hunting, target shooting, collection, according to GunPolicy.org.