It happened in the area of Addison and Lincoln.
Slashed and punctured tires. This was the unpleasant surprise that resident after resident of this North Side neighborhood woke up to.
"I went to get into the one van to go, two flat tires," said Tim Humprey. "Used the spare van, found three flat tires on that one."
"My daughter's got one, and four cars of mine," said Al Martinez.
The vandalism appears to have been committed overnight in the blocks surrounding the Addison Street Brown Line. While some called AAA for help, others joined together to aid those who were hit.
"We're just helping people out," said Steve Kovalec. "Maybe some people can inflate, change their spares...I don't know if they were having fun. Don't know what this was about to tell you the truth."
Police don't have any suspects yet, and it's not immediately clear whether more than one person was involved.
Cab driver Folarin Odusanya pulled out of his overnight parking spot only to find he had been a victim as well.
"I've seen a lot, people do stuff, some are so angry with life and with themselves," Odusanya said.
Police don't know how many vehicles had their tires slashed. ABC7 walked the neighborhood and counted 22, but the final number is likely even higher.