It happened at the Somers House, a tavern near the shore of Lake Michigan that's popular with people from the Carthage College community down the road, the Kenosha News reported.
As of 2:30 a.m. local time, police had established a radius extending three blocks south of the bar as officers searched for the suspect, the News reported.
The count of three fatalities came from the Kenosha County Sherriff's Department, according to tweets from WDJT-TV reporter Brittany Lewis in Milwaukee and N. Nieves of CBS News.
This is a developing story. Check back for updates.