Users who attempted to access the firm's mobile app to book a car have been met with a notice which says that services are not currently available and the company will "provide an updated as soon as possible."
Daimler-owned Car2go is keen to emphasize, however, that vulnerabilities or security problems with the mobile app -- which are used to unlock the cars -- are not at fault. In response to a tweet sent out by Automotive News, the car hire firm said:
"We were not hacked. This is an instance of fraud, isolated to Chicago, and we are currently working with law enforcement. None of our member's personal or confidential information has been compromised. No other SHARE NOW North American market has been affected."
A spokesperson told CBS Chicago that "out of an abundance of caution" services have been paused in the city.
The Chicago Police Department has also been notified and is investigating how the vehicles were acquired, some of which have been recovered. Law enforcement is not sure at the present stage whether there are other vehicles involved in the fraud which are unaccounted for.