CHICAGO – What officials say is an outbreak of the "stomach flu" in the Cook County Jail has prompted the sheriff to quarantine one of the jail's largest divisions.

Sheriff Tom Dart says the bug causes diarrhea and vomiting and has hit the largest minimum security division in the Chicago facility that houses just under 700 inmates. Dart says about 30 inmates are now "really sick." He says it's unclear how long the quarantine will last.

The outbreak has made running the jail more complicated because minimum-security inmates typically work in the jail's kitchen and transport meals. Dart says, if those inmates can't perform those duties, he may be forced to use medium-security inmates who require more supervision from correctional officers. That could drive up costs.