A huge search and rescue effort is underway to find survivors in the wake of the partial collapse of the building in Surfside, Florida.
Video of the collapse showed the sea-facing side of the 12-storey residential building tumble into a pile of rubble and a huge cloud of debris blanket the neighbourhood north of Miami Beach.
Surfside Mayor Charles Burkett confirmed at least one person was killed in the collapse and ten people were treated at the scene.
It is not known how many people were in the building at the time or how many have been injured in total.
Some of the units in the building are owned by vacationers and they may not have been staying in the building at the time.
Surfside Commissioner Nelly Velasquez said that more than 50 people were unaccounted for following the collapse.
Miami-Dade Fire Rescue officials said 35 people were rescued after 55 apartments collapsed, and that two people had been pulled from the rubble.
Firefighters used truck-mounted ladders to rescue people trapped on balconies.
“The building is literally pancaked, it has gone down, and I mean there’s just feet in between stories where there were 10 feet,” said Mr Burkett.
“That is heartbreaking because it doesn’t mean to me that we’re gonna be as successful as we would want to be to find people alive.”
And he added: “Well, what we know is they were doing roof work on the building at the time. Certainly, that doesn’t seem like it would be the issue that would have caused it.
“Some of the residents at the community center have complained to me that the new building that went up to the south used to shake the building when they were putting the pilings in, but I think that we need to look very hard at what happened there and find out because buildings just don’t fall down like this.
“They just don’t fall down like this. It’s less likely than a lightning strike. It just doesn’t happen. You don’t see buildings falling down in America.”
Authorities have used live-victim dogs to search the site for survivors and teams are using camera and sound equipment at any areas identified by the K9 teams.
Florida Governor Ron DeSantis toured the site on Thursday.
“TV doesn’t do it justice, it is really traumatic to see the collapse of a structure like that,” said Mr DeSantis.
“We still have hope to be able to identify additional survivors.”
Officials have not yet given a cause for the collapse, and Mr DeSantis said that engineers would be looking into what happened.
Miami-Dade County’s Technical Rescue Team was being assisted by city fire departments in the search for survivors.
“It’s a very active scene, I advise everyone to just stay out of the area so that fire rescue and officers can conduct rescues and do what we need to do,” said Surfside Police Sgt Marian Cruz.
The Champlain Towers South Condos was built in 1981 and has 136 units.
Miami-Dade Mayor Daniella Levine said she spoke with Joe Biden by phone and that the president had offered the full support of the federal government.
City of Surfside state Senator Jason Pizzo said in a statement that it was “an unimaginable tragedy that will require our attention in the hours, days, and weeks to come, and we will provide the needed support and comfort to our fellow neighbors and residents as they navigate this enormously difficult time.”
Miami Heat basketball player Tyler Herro and assistant coast Chris Quinn helped dish out water and food at the scene.
“We were devastated to hear of the catastrophic Champlain Towers building collapse in Surfside,” the NBA team wrote on Twitter.
“Our hearts go out to the victims and their families. We are thankful for the first responders who are working around the clock in rescue efforts.”
Barry Cohen, who has lived in the building for three years, was asleep with his wife when they heard what they initially thought was a thunderstorm.
“It just kept on going for like 30 seconds and my wife and I got whatever we could together and we went to leave our apartment and we opened up the door and there was a huge pile of rubble and dust and just havoc,” he told 7News.
“What we did was, we went to the stairs and we rushed down the stairs. When we got to the bottom of the stairs, we couldn’t open the door because the steel had bent in the door, and all this stuff was preventing us from being able to go there.”
Mr Cohen said the couple then returned to their unit and were hoisted to safety by rescue crews.