A second-story apartment floor collapsed late Saturday night during a party, sending people tumbling to the first floor.
It happened at 135 South 6th St. in downtown La Crosse.
Three people were hospitalized after the floor collapsed right under their feet.
According to the building's owner, Nate Brooks of River City Rentals, the apartment's tenants said those three people have been released from the hospital.
Brooks also said, when he got to the scene, he found multiple beer kegs where the floor had collapsed.
Sixth Street resident Larry Klahn heard loud music a few buildings down the block Saturday night, but didn't think much of it. He was used to a lot of noise.
"I insulated the walls a lot so I wouldn't hear a lot of traffic sounds and stuff like that. So I didn't know what had happened," said Klahn.
Until he got a worried phone call. "A friend of mine called me that was driving by and asked me what was going on on my block," said Klahn.
He went downstairs and found the street full of fire trucks, ambulances and police cars.
At around 11:00 p.m., the floor of a second-level neighboring apartment collapsed.
Up to 50 people were in the apartment when a 30-by-30-foot area of the second floor, to the rear of the building, caved in.
Security video from News 8 shows dozens of people climbing down from the roof of the building next door.
La Crosse Fire Department Division Chief Mark Amann said he'd never seen anything like it. "This is kind of an odd case that we're still investigating," said Amann.
Firefighters searched the building, making sure no one was trapped under the rubble. "We did not find anybody else in there at that time. Everybody had self-evacuated themselves out of the building. So we did not have to get anybody that was tangled up or any debris on them. We didn't have anybody trapped in there," said Amann.
Three injured people were treated at the scene and then Tri-State Ambulance took them to the hospital.
At around 1:00 a.m. on Sunday, a city building inspector condemned the building.
As Klahn watched the fire trucks clear out of his block, he said one thing was going through his mind. "If you put that many people out on a floor in an old building that was never meant to do it, bad things are going to happen sooner or later," said Klahn.
The apartment building and the empty commercial space below it have been condemned, but the art studio on the first floor, called Vitamin Studio, is still safe.
The five tenants who lived in the apartment now have to find somewhere else to sleep.
The damaged building is a historic site in the city, as the original location of Trane Company.
It was built in the early 1900s, but Brooks said he thinks the damaged apartment unit on the second floor may have been built at a later date.