Violence explosion: Killings in Chicago suburbs have increased 50% this year Chicago police plan for July 4th weekend amid surging violence Chicago Police Supt. David Brown says police days off have been canceled and extra officers will be deployed this holiday weekend. CHICAGO - Chicago Mayor Lori Lightfoot is blaming two mass shootings over the weekend on battles between street gang factions. "Incidents like these are both heartbreaking and frustrating," she said Monday. The Cook County Medical Examiner says the explosion of violence this year is also engulfing suburban communities. Dr. Ponni Arunkumar says there has been a 50 percent increase in suburban killings so far this year: 100 homicides since January 1st, compared to 66 last year.