In Chicago, a wave of violence over the long holiday weekend left 102 people shot—with 15 people killed and 86 others injured by gunfire.  Nearly half were shot in a spate of violence as the weekend closed out between 3:30 p.m. Tuesday and 3:30 a.m. Wednesday.

The weekend began with 19 people shot on Friday night and 23 on Saturday.  Sunday and Monday nights were both relatively quiet, by summer standards, with 17 people shot over the two days, according to Tribune data.

Violence in Chicago has become the standard as the city is plagued with gang activity.  The Chicago Police Department says that it has become standard procedure during long holiday warm weather weekends to put more than 1,300 extra officers on the street.  A total of 159 guns were seized by Chicago police since Friday. The violence this year was largely concentrated in the city’s south and west sides, including districts where the Chicago Police Department have deployed extra resources including hundreds of officers on overtime.

The Chicago Police Department expressed frustrations over the violent long weekend.  They said they are conducting “a very comprehensive review” after experiencing one of its most violent Fourth of July weekends in recent history.  Chief police spokesman Anthony Guglielmi said “It’s perplexing, the mood here is frustration.”  “We deployed some very successful tactics over the Memorial Day weekend.” Yet those same tactics did not seem to work as well over the Fourth holiday.”

A lot of the shootings appeared to be over “petty disputes that escalated into somebody pulling out a gun.”  He mentioned some examples: A shooting in Smith Park that started as an argument over where people were sitting; a confrontation between a driver and bicyclists on State Street, with the driver getting a gun from his trunk and officers intervening. He said a “handful” of shootings were “retaliatory .. People drinking all day and then things escalating … It’s just enormously frustrating.”

As part of its review of what happened over the weekend, the department is looking at how amateur fireworks may have interfered with the ShotSpotter system, a relatively new technology the department hopes to expand.  The spotters register a shooting and deploy cameras in the direction of the shots while officers are deployed.  Analysts at the district station look at the data in real time to decide what steps to take next.  Guglielmi called it “micro-deployment.”

The violent weekend brings the total number of people shot in Chicago so far in 2017 to more than 1,800, according to data maintained by the Tribune, still below the 2,035 recorded at this time last year.