PORTLAND, Maine (AP) — An empty housing unit at the Cumberland County Jail has been converted to an infirmary following an increase in the number of confirmed swine flu cases.

Sheriff Mark Dion said Monday that three inmates have been infected by the H1N1 virus and three other inmates are showing symptoms.

A fourth person with the virus, a 41-year-old federal detainee, was released on bond Friday night after immigration officials determined that he would not be held pending an immigration hearing.

The Portland Press Herald quoted Dion as saying the man, who was no longer showing symptoms of the illness, was transported back to Massachusetts.

All positive and suspected cases have been assigned to a single housing unit that has a capacity of about 50 inmates.