First Avenue in Minneapolis is one of the nation’s most venerated nightclubs. It opened in 1970, and it’s famously the place where Prince shot Purple Rain. But it’s an old building; it first opened as a Greyhound bus depot in 1937. And last night, during a show there, a big piece of its ceiling collapsed and fell on the crowd, injuring at least three people.

The Minneapolis Star Tribune reports that the Canadian metal band Theory Of A Deadman was about a few songs into its headlining set last night when a 30-foot-by-30-foot section of the ceiling gave way. Venue general manager Nate Kranz says, “A large portion of the ceiling fell and took out water pipes with it. We have no idea why or how it happened. We won’t know anything about this until tomorrow. It was a terrible surprise.” Three people were taken to the emergency room, and all are in satisfactory condition, without life-threatening injuries.

Immediately after the collapse, security evacuated from the club. (The Star Tribune quotes one concertgoer who immediately thought the dust and screaming was part of the show.) The club is closed to day, and inspectors are looking into the collapse. Club employees don’t yet know if they’ll have to shut down operations, or for how long. Kranz says, “If I’m told we’re going to be dark, we’ll have to figure that out.”