Seven people, including the shooter, were killed in a shooting on a company campus in Milwaukee in the U.S. state of Wisconsin on Wednesday, local media reported.

The shooting rampage took place on the Milwaukee campus of beer brewer Molson Coors. The company notified its employees at the complex of an "active shooter" by email, according to Milwaukee Journal Sentinel.

The Milwaukee Police Department said in a series of tweets that it was investigating "a critical incident" and responding to "an active scene," urging people to stay away from the area.

The campus was on lockdown, Milwaukee Journal Sentinel said, citing Twitter posts from witnesses.