Dozens of people armed with pillows showed up in front of the Art Institute on Michigan Avenue to do battle at 2 p.m. But police stopped the pillow fighting after about 20 minutes.
Police told nbcchicago.com that there was no concerted effort to crack down on the event -- which went off without a hitch last year -- but responded after receiving 911 calls.
"They were causing a disturbance on the public way as part of a non-permitted event. They were told to stop and refused to so," CPD Officer Dan O'Brien said.
Police said everything would have been fine if the participants had followed the proper procedures and obtained a permit beforehand.
Four people were cited for disorderly conduct and casting refuse on the public way. Police said nobody was taken to jail, but pictures from the event show that some people were handcuffed.
According to www.groundreport.com, security officers with the Art Institute seemed to be amused by the whole thing, but CPD officers referred to the participants as "protestors" and "knuckleheads."
The local event was organized by the Pillow Fight Club, but as of this writing, there were no updates on their Web site about what went down on Saturday.
According to the guidelines set before the event, participants were asked to bring a soft pillow and wait for the signal. The organizers urged people to swing lightly, remove their glasses, obey the signals and to clean up your mess.