Two people are in custody after a Sunday morning shooting left 13 injured, four critically, at a Chicago memorial for a victim of gun violence, police said.

The shots began about 12:35 a.m. after a “verbal altercation” in a home in the city’s South Side, according to police, and continued as people fled from a party that some at the scene told the Chicago Tribune was held to mark the birthday of a 22-year-old who was fatally shot in April.

The shooting, which police called an “isolated incident,” unfolded in a city that has struggled to curb high rates of gun violence amid national scrutiny, though homicides have dropped since a dramatic peak in 2016. Police say shootings in the city are on track to decrease again this year, but Sunday’s tragedy raised familiar frustrations among residents and local officials.

“Very sad and very disappointed that our children, this is their welcoming not only into the Christmas holiday but to their Christmas break,” said the city’s 16th Ward Alderman Stephanie Coleman, recalling how eight calls from block residents led her to the grim scene in the neighborhood of Englewood – where the early-morning chaos brought kids outside.

“I saw disappointment, I saw frustration, I saw fear,” she said. “I saw lots of concerned neighbors getting to the bottom of it.”

Police said they are questioning two suspects, one who was injured and another who had a revolver, according to the Tribune.

Two people appeared to be “shooting randomly at people as they exited the party,” Chief of Patrol Fred Waller told reporters, according to the Tribune, describing more shots at another location nearby.

Cameras captured part of the violence, and technology that alerts officers to the sounds of shots brought authorities to the scene within minutes, police said.

Authorities said those who went to the hospital with gunshot wounds range in age from 16 to 48. Police said the youngest victim was in stable condition Sunday morning, ABC Chicago reported, after wounds to the back and chest left him in critical condition.

Police described the injured suspect as a 25-year-old man who went to a hospital with “serious” injuries.

Investigations are ongoing, and further details from police were not available Sunday morning.

The incident brought a massive police response to the scene. Area resident Terence Daniely told the Tribune that he woke to see a street filled with cars and ambulances.

The 57-year-old lamented the “reckless” violence on the block, where he has spent about four years.

“How does it continually happen?” he told the Tribune. “When is it going to stop?”

It wasn’t the first time that a Chicago memorial to a shooting victim ended in more violence: Gunfire at a 2017 vigil wounded a 12-year-old boy and six others, the newspaper reported. A spike in crime the year before, when Chicago’s homicides topped those in New York and Los Angeles combined, was already sparking renewed national attention – including from President Trump, who has called throughout his term for action to address the “carnage.”

Trump criticized Chicago’s law enforcement at a national gathering of police chiefs this fall, targeting the police superintendent, who said he chose not to attend the event because it “doesn’t line up with our city’s core values.” The president called the Chicago violence “embarrassing to us as a nation,” claiming the country’s third-largest city is less safe than Afghanistan and suggesting without details that its crime rates could easily be brought down.

Police have pushed back on Trump’s statements, pointing to double-digit decreases in crime in recent years. Discussing the president’s address, then-Police Superintendent Eddie Johnson – fired this month over what Chicago’s mayor called “ethical lapses” – rebuked “the national narrative that Chicago is a city on fire.”

Johnson also repeatedly disputed the idea that there’s an easy fix for the violence in the city.

“If you have a magic bullet to stop the violence anywhere, not just in Chicago but in America, then please, share it with us,” he said once in response to the president.

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