First Avenue will stay closed until the plaster ceiling at the nightclub is fixed following a partial collapse that sent three people to the hospital.

No cause for the collapse had been announced as of late Thursday and officials said they may never be able to determine why a portion of the ceiling fell down during a Wednesday night concert.

"Frankly, I'm not sure that anybody will ever be able to come in and just pinpoint 100 percent here's what happened," First Avenue general manager Nate Kranz said Thursday. "It's extremely unfortunate and kind of a freak accident."

About a 30-by-30-foot section of the ceiling gave way during a concert around 10 p.m. Wednesday, the Minneapolis Fire Department said. Three people were injured and went to Hennepin County Medical Center. None of the injuries appeared to be life-threatening.

The damage was limited to the performance area of the club. The adjoining restaurant will be allowed to open once the fire sprinkler system can be restored, city officials said.

Plans are for the ceiling in the music venue to be demolished and a damaged sprinkler system to be repaired, city officials said. The city will inspect all of the fixes before the club is reopened to the public, said Patrick Higgins, a building official with the city.

The city issued a demolition permit to begin work on the ceiling Thursday. Minneapolis building inspectors as well as insurance representatives were on site at First Avenue throughout the day. The ceiling, which dates to 1936, was being tested for asbestos before demolition could begin, Kranz said. Equipment inside the venue was moved to prevent damage, he said.

No cause as yet

An engineer who visited the site could not find the exact cause of the collapse, but it was determined that there was not any immediate danger such as structural damage to the building, Kranz said.

"We're glad it wasn't worse than what it was," he said.

The club announced it will be closed Thursday and Friday to assess the damage. It is still unclear when First Avenue will reopen.

First Avenue's last full commercial inspection was in 2013, and no violations were found, said Kris Johnson, who works with the city's fire inspection services. The next inspection was supposed to occur in 2018.

Building inspectors check for visible issues such as loose wiring or water damage, and will write orders if violations are found, said a city spokesman.

According to city inspection permit records, most of the recent permits that the city issued for First Avenue appear to be for routine maintenance like commercial hood cleaning. The last permit for remodeling was issued in 2011 and included installing new accessible ramps inside.

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.

Determining the cause of the collapse is not what's paramount to the city, Higgins said.

"We don't need to know what happened, we just need to know that whatever repairs were going to be done we have a safe place after they completed it," he said.

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.

One of the best known music rooms in the United States, the 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.

On Twitter Thursday, the venue sent out a statement to its fans saying, "We're working with city inspectors and structural engineers to discover the reason this happened and how best to reopen safely. … Our thoughts and hearts are with those who were injured. Thank you for all of your support!"

Some fans and musicians took to social media to respond with well wishes.

Hip-hop artist Lizzo tweeted, "Get well soon, @FirstAvenue."

Staff writers Mary Lynn Smith, Liz Sawyer, Jon Bream and Chris Riemenschneider contributed to this report.

Nicole Norfleet • 612-673-4495

Twitter: @nicolenorfleet