Following another night of springtime chaos downtown, Mayor Lori Lightfoot on Sunday announced she’s banning minors from Millennium Park on weekend evenings unless they’re accompanied by an adult.

Declaring the city “cannot allow any of our public spaces to become platforms for danger,” Lightfoot said unaccompanied minors won’t be allowed in one of the city’s most iconic tourist attractions after 6 p.m. from Thursday through Sunday, unless they’re with “at least one responsible adult.”

The mayor announced that measure after a frenetic stretch from Saturday evening into early Sunday that started with crowds of young people congregating in the Loop — and ended with a 16-year-old boy fatally shot near “The Bean,” two men wounded in a separate attack nearby and 26 juveniles and five adults arrested.

“Tragically, a young person — a teenager — lost his life last night in Millennium Park,” Lightfoot said in a statement Sunday announcing the 6 p.m. curfew. “I suspect an overwhelming majority of the youth who were in the park were there to have a good time and enjoy a summer evening. But the scene devolved into one of chaos and unnecessary violence.”

The new policy “will be strictly enforced and violations will be dealt with swiftly,” according to Lightfoot, who added: “Anyone coming into our public spaces should expect to enjoy them peacefully and must respect and exhibit basic community norms of decency. We simply will not accept anything less.”

Chicago Police Department Superintendent David Brown wouldn’t give specifics on how officers will enforce the new policy.

“It’s got to be strategic and surgical in the way we do it, one step at a time instead of this broad measure that you might have to pull back because it’s too broad and not effective,” Brown said during a news conference Sunday afternoon.

The ACLU of Illinois said Lightfoot’s rule suggests the park “should not be available for all residents of Chicago.”

“The vague description — relying on an undefined ‘responsible adult’ — allowing young people to be present in the park and the promise of strict enforcement will result in unnecessary stops and arrests and further strain relations between CPD and young people of color,” Ed Yohnka, spokesman for the ACLU of Illinois, said in a statement.

Police said eight guns were recovered in connection to the “disturbances involving large crowds in the downtown area,” which came just three days after an unsanctioned North Avenue Beach “takeover” gave way to similar mayhem on the Near North Side that didn’t grow violent.

Brown said the department is monitoring social media accounts that share locations for the meet-ups, which they’ve found to be run by young people. The department is looking into whether they can charge the owners of those accounts with inciting the gatherings.

“We want to hold people accountable for the promotion leading to the behavior,” Brown said.

The situation on Saturday escalated about 7:30 p.m., when Seandell Holliday was shot in the chest in the 200 block of East Randolph Street near the iconic “Cloud Gate” statue more commonly known as “The Bean,” according to police and the Cook County medical examiner’s office. The teen was rushed to Lurie Children’s Hospital and pronounced dead.

A 17-year-old boy was arrested by police moments later and charged with second-degree murder, aggravated battery and unauthorized use of a weapon, police said. A 16-year-old was also arrested with a “ghost gun” near the scene, Brown said.

The shooting comes days after another attack on Tuesday evening, when a 19-year-old man was wounded by gunfire near “The Bean” as he rode in a car in the first block of North Michigan Avenue, police reported at the time.

Lightfoot called Saturday’s fatal shooting “utterly unacceptable.”

“Tonight, a mother is grief-stricken, mourning the loss of her child and searching for answers,” Lightfoot said. “My heart is breaking for the mother as she grieves this unspeakable loss.”

At the same time, she also urged “parents and guardians to step up, to ensure that your children understand basic values of respect, and that you take responsibility for knowing at all times where your children are and who they are with.”

Later Saturday, as officers attempted to disperse the large crowd moving through the downtown area, police said two men were wounded in a separate shooting in the 300 block of South State Street, less than a mile away from “The Bean.” They were among a group walking in the area around 11:40 p.m. when two people started shooting at them.

One of the men, thought to be between 18 and 20 years old, was struck in his neck and chest and taken to Northwestern Memorial Hospital in critical condition, officials said. The other man, 18, was shot in the hand and taken to Stroger Hospital in good condition.

Two minors were taken for questioning, police said.

On Sunday morning, police released a preliminary statement reporting at least 26 minors and four adults had been arrested in relation to the disturbances downtown.

Five of the arrests were for gun-related violations, and seven firearms were recovered, police added. At least two officers were hurt.

Ald. Raymond Lopez (15th), a mayoral candidate and one of Lightfoot’s fiercest City Hall critics, said what’s currently playing out in Chicago is “beyond disheartening,” not “beyond repair.” He insisted the most pressing issue is inaction from Lightfoot and other leaders, not “the youth coming to downtown.”

“Their individual and collective silence gives permission for this behavior to continue,” Lopez wrote on Twitter on Sunday. “We will only change Chicago’s trajectory if people have the courage to speak out.”