An employee of the brewery killed five of his collaborators in the city of Milwaukee in the United States before shooting the gun.
Filming took place at Molson Coors Brewing Co at 14:00 local time on Wednesday.
The campus has more than 20 buildings: a mixture of brewing facilities and corporate offices, which employ more than 1,000 workers.
Milwaukee Mayor Tom Barrett said: “There were five people who went to work today, just like everyone goes to work, and they thought they were going to work, finish the day and return to their families.
“They didn’t – and tragically they never will.”
Police did not discuss the 51-year-old assassin’s motive.
Police chief Alfonso Morales after the shooting said: “There is no threat at this time and we will continue to investigate all night.”
Morales said that bloodshed was limited to the Molson Coors facility and that “no audiences were involved.”
United States President Donald Trump spoke briefly about the shootings ahead of a press conference on the coronavirus, saying: “Our hearts are broken for (the victims of the shooting) and their loved ones.
“We send our condolences. We will be with them, and it’s a terrible thing, a terrible thing.”
Trump described the gunman as an “evil assassin”.
Earlier, on Twitter, the brewery wrote: “There is an active situation in our Milwaukee facility and we are working closely with the Milwaukee police department.
“Our top priority is our employees and we will provide updates in collaboration with the police, as far as we can.”