Three people face charges of reckless conduct and possession of a paint/pellet gun, just as a community activist put out a warning on Wednesday of such weapons being fired from moving vehicles.
"These perpetrators are opening up van doors, they're rolling down windows, they're aiming this weapon -- which is a paintball gun -- high powered, at the individuals and discharging it," community activist Andrew Holmes told NBC Chicago.
On Wednesday, one man said he was shot by a paintball gun near 85th and Laflin. The man and his truck were both struck with yellow paintballs, Holmes said.
Legal paintball courses require protective vests and goggles, and without such protection the weapons can cause serious injuries, especially to the eyes.
Police said the three people arrested Tuesday night -- two 16-year-olds and a 27-year-old -- had three weapons with them. All three face misdemeanor charges.
A Chicago Transit Authority bus driver who spoke with NBC Chicago said he saw a bus with paint pellets shot all over it on Tuesday night.
"That's the norm," said Gail Beloch. "This is Halloween. That's what they do."
Beloch said drivers wear shields to protect their eyes from paintball shooters during the holiday.
A driver of a tractor-trailer last week was struck in the face by a paintball as he waited to enter the Chicago Skyway. It was unknown, however, if those arrested on Tuesday had anything to do with either of those incidents.
"This is every day," said Holmes. "But with the increase of children on the streets [Thursday], they think it's a joke. They want to target children, they want to target the mothers and fathers that are walking with them."