At least 75 people were shot in one of the most violent weekends this year, spurred by a seven-hour period early Sunday when 40 were shot.
Of the wounded who gave their age, the oldest was 62 and the youngest 11, according to police records.
US President Donald Trump has repeatedly vowed to intervene in Chicago, and a year ago he said that crime and killings had reached "epidemic proportions" in the city.
Although the drop was significant, it exceeded the combined number of killings in New York City and Los Angeles, which are the two USA cities bigger than Chicago. "This is a small subset of individuals who think they can play by their own rules because they continue to get a slap on the wrist when we arrest them", Johnson said. "We together have to work as a city.we have a challenge and it requires all of us".
He said the police department is working to prevent crime. But murders were down 23% compared to same point past year, and the city tallied 19% fewer shooting incidents.
"What happened this weekend did not happen in every neighborhood of Chicago but it is unacceptable to happen in any neighborhood of Chicago", the city's mayor, Rahm Emanuel, told reporters on Monday. More from ABC11: Henderson march organizers urge end to city violenceThe most recent shooting took place near the 2600 block of South State Street just before 8 p.m. Fox News itself has reported that 63 people were shot - not murdered - while, in fact, ten were killed.
Police also noted that numerous shootings were in four police districts, including the West Side's Harrison, Ogden and Austin police districts, that have struggled with violent crime this year.
June marked 15 straight months of fewer killings and shootings, police said.
Giuliani cited the murders as an endorsement for former policeman Garry McCarthy for mayor, who Giuliani says can lower the city's homicide rate.
The police chief emphasized an oft-repeated criticism by city officials that repeat gun offenders receive sentences that are too short and are able to quickly return to the streets to commit more crimes - believing they will not face serious consequences.
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