Via Ald. Cappleman's website:
"I am working with the police and community members to find out more on what happened last night on Leland. I want to thank the neighbors that called 911 immediately to alert the police. Anyone with property damage please contact the police immediately. Anyone with information please contact the police and my office. I’ve requested more police be in the area tonight in case of another incident. Do not hesitate to call 911 if you see anything suspicious."
Update: It now appears, according to the Alderman, that a birthday party held at Chase Park with close to 50 kids/teens was the source of the mob.
Media coverage of the incident:
WGN: Video captures vandals damages slew of cars in Uptown
DNAInfo: Dozes on Kids Terrorize Motorists, Damage Cars in Uptown
Fox 32 News: No arrests after reports of 'wilding' reported in Uptown