There was heavy rain and flooding in the south Chicago neighbourhood Wednesday night, but officials say it's not clear if that's what caused the ground to open up.
There were two vehicles in the hole when fire officials arrived at 5:30 am, but then a third car fell in as the crater continued to expand.
A man was pulled out of the crater and taken to hospital in South Deering after the ground gave way and his car tumbled in.
There were reports that he was trying to drive around the hole when the road caved in and he fell inside while in his vehicle.
Firefighters and police have stayed on the scene trying to keep any spectators away.
With files from CNN