WINDSOR, Colo. (CBS4)- Several people have gotten sick after swimming in Windsor Lake. That lake is off limits for swimmers until further notice.

The Colorado Department of Health confirms the illness. Weld County health officials said the Shigella bacteria is to blame.

Shigella causes stomach cramps and fever one to four days after getting infected.

Persons with mild infections usually recover quickly without antibiotic treatment. However, appropriate antibiotic treatment kills Shigella bacteria, and may shorten the illness by a few days.