A ceiling collapse at the legendary downtown Minneapolis nightclub First Avenue sent three people to the hospital Wednesday night, and Minneapolis firefighters are evaluating the integrity of the building.

A 30-foot-by-30-foot section gave way during a concert about 10 p.m., the Minneapolis Fire Department said.

“A large portion of the ceiling fell and took out water pipes with it,” said Nate Kranz, First Avenue general manager. “We have no idea why or how it happened. We won’t know anything about this until tomorrow. It was a terrible surprise.”

Kranz said a couple of people were taken out by ambulance. Hennepin County Medical Center spokeswoman Christine Hill said three people were brought into the emergency room and are in satisfactory condition with non-life-threatening injuries.

The ceiling that collapsed was over the balcony DJ booth at the back of the dance floor, Kranz said. A section fell onto the floor about midway through the headlining set by Canadian metal band Theory of a Deadman. The show was stopped, and the 1,000 or so fans were immediately evacuated. Fire crews responding to the club shut off water to the area, the Fire Department said.

Todd Johnson, of Elk River, was at the concert with his family and said the band had just finished its fourth song, when the musicians suddenly ran offstage.

Then he saw that a part of the ceiling had fallen and water was streaming from the ceiling.

Gallery: Gallery: Scene after First Avenue's ceiling collapses Gallery: Gallery: Scene after First Avenue's ceiling collapses

About a minute later a second piece of the ceiling fell, he said. At first some people thought the water was coming from the sprinkler system, but there was too much for that to be the source.

Whoa! Came out to First Ave to watch our friends in @toadmofficial and the ceiling collapsed!!! Hope everyone is ok! #ceilingfalling #3pillmorning #theoryofadeadman A video posted by 3 Pill Morning (@3pillmorning) on Aug 12, 2015 at 8:39pm PDT

Jennifer Johnson said the second piece that fell was twice as big as the first, prompting some screams from the crowd.

Denay Riser, of White Bear Lake, said there was smoke everywhere and some screaming, but she didn’t think anything of it at first because she thought it was part of the show.

At that point, said Nathan Boyd, the staff advised everybody to walk out. The evacuation was orderly, he said.

Mersadees Sten of Gilbert, Minn., drove to town for the concert with her friend Eric Johnson, of Virginia.

They were standing by the stage when they heard a noise like rushing water and saw the band jump off the stage. Then a huge chunk of ceiling fell behind them.

A handful of people received minor injuries. One woman near the falling tile was bleeding and immediately tended to by paramedics.

“It seemed completely random. People were yelling to get the hell out,” Sten said.

She said they had been standing in that spot a few minutes before, so they were very lucky. “For whatever reason we decided to get closer to the stage,” she said.

Other fans said they were impressed with the staff’s handling of the situation.

One of the best known music rooms in the United States, the landmark nightclub opened in 1970 and has since presented a who’s who of popular music, from Tina Turner and U2 to Jessie J and Prince, who famously filmed his 1984 movie “Purple Rain” there. The building was originally a Greyhound Bus depot, which opened in 1937.

The Mann theater family sold the building in 2000 to First Avenue’s ownership team at the time, including longtime accountant Byron Frank, whose daughter Dayna Frank and their family are the current owners.

The club installed a new lighting rig over its big stage a few weeks ago, but Kranz said the work done on that was on the other side of the room from where the pieces fell and likely not a contributing factor. In fact, he said, “That was another case where we just had [inspectors] in here looking everything over.”

Kranz said the club will be closed Thursday, and inspectors will be in the club Thursday morning to determine “how it happened and what to do to fix it so it doesn’t happen again.”

The scene at First Avenue after the ceiling collapse Wednesday night.

As for upcoming shows, she said, “If I’m told we’re going to be dark, we’ll have to figure that out.”

No band was scheduled for Thursday. On Friday, the bluegrass band Ginstrings is scheduled, and Saturday a sold-out show by Grammy winning R&B star Miguel.

“That’s the big one,” Kranz said.

Beyond that, though, next week is uncharacteristically quiet for the club, aside from shows in its neighboring small 7th Street Entry.

Staff writer Chris Riemenschneider contributed to this report.