The Chicago Police Department plans to deploy off-duty officers on overtime pay to 20 of the city's most dangerous parks.
The force is already under City Council scrutiny for overtime spending that's expected to total $100 million through the end of the year.
The Chicago Sun-Times reports the new park patrol initiative will rely on money from the Park District Budget.
It starts this month and will cost about $250,000 through the end of the year, with another $4 million budgeted for next year.
Mayor Rahm Emanuel calls it a "critical effort" that will help keep the city's parks safe and encourage parents to enroll their children in Park District programs.
Police would not identify the parks involved. They were chosen based on three years' worth of crime data.
Witnesses said several gunmen fired at least 20 shots at a group gathered at Cornell Square Park, on the 1800 block of W. 51st Street, shortly before 10:15 p.m. The spray of bullets sent a mass of people to the ground on the basketball courts.
McCarthy said an assault-style rifle with a high capacity magazine was used in the shooting, and that it appeared to be gang-related.
"The parks in the city of Chicago belong to the families of the city of Chicago, the streets of the city of Chicago belong to families of Chicago, the front stoops of our homes belong to the families of the city of Chicago," said Mayor Rahm Emanuel. "You go out there and enjoy our city because they do not own or belong or have no place for gangs. And assault weapons do not belong in our parks, they do not belong on our streets."
Emanuel asked that parents and families continue to go out into the community.
McCarthy on Thursday said his department is on track to spend $93 million in overtime this year -- nearly triple the amount originally budgeted -- but pushed back against an assertion that means there aren't enough officers.
To fight a homicide rate that put Chicago in the national spotlight, as many as 400 officers each night have been working overtime and saturating high crime areas.
"With the distribution of the rookie officers ... we made a decision to kick off Operation Impact with overtime," McCarthy said in answering a question from Ald. Ricardo Muñoz (22) as to why overtime is "so out of control."
"It's cheaper to pay a police officer overtime than it is to hire a fully loaded -- with benefits, health benefits and pay -- officer," said McCarthy.