The first incident occurred near Chicago and Michigan avenues at about 6 p.m. Saturday, the Chicago Sun-Times reported. Officers came across "a number of kids fighting amongst themselves," police spokeswoman Amina Greer said.
The Chicago Tribune reported at least 50 teenagers were running through the streets, blocking sidewalk and street traffic, and bumping into passersby. Officers arrested two adults and 15 teenagers and charged them with one count each of reckless conduct, officials said.
In a separate incident, police arrested 11 teenagers at a Chicago Transit Authority elevated train station in The Loop about 6:30 p.m. Saturday, the Sun-Times said.
The teens allegedly accosted a group of women aboard a train car, police said. They then got off the train with a purse belonging to one of the victims.
Police stopped them before they left the station and made the arrests.
The 11 teens were all charged with battery. Two of the suspects were also charged with strong-arm robbery, police said.
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