Multiple people have been killed in a shooting at a major brewing company in the US.

Milwaukee Mayor Tom Barrett said there had been a shooting at the Molson Coors Brewing Company campus but did not give the exact number of people killed. He said the gunman had been killed.

He called it “a horrible, horrible day for the employees here”.

He said: “What has happened is there was a horrific shooting that has occurred.

“We’re urging all residents and people in this area to stay away from this area. … They’re continuing their sweep to make sure there is nothing more that’s occurring. It is a horrible, horrible day for the employees here. It’s a very rough day for anyone who is close to this situation.”

Police tweeted that there was no longer an active threat.

The shooting occurred at a sprawling complex that includes a mix of corporate offices and brewing facilities.

At least 600 people work at the complex, which is widely known in the Milwaukee area as Miller Valley, a reference to the Miller Brewing company that is now part of Molson Coors.

James Boyles told the Milwaukee Journal Sentinel that his wife, Lasonya Ragdales, works at Molson Coors in the claims department.

She was texting from inside the facility and told her husband that there was an active gunman and she was locked in a room with a bunch of co-workers, the Journal Sentinel reported.

Milwaukee Shooting
Police respond to the shooting at the Molson Coors site (Morry Gash/PA)

Miller Valley features a 160-year-old brewery, with a packaging centre that fills thousands of cans and bottles every minute and a distribution centre the size of five football fields.

The facility is also home to corporate customer service, finance, human resources and engineering.

Tours take people to underground caves where beer was once stored, a saloon with intricate woodwork, a beer hall with stained-glass windows, a champagne room meeting hall with leaded-glass windows, and an outdoor beer garden that can hold 300 people.