Rescuers brought 35 people out alive from the collapsed 12-storey building in Surfside, north of Miami Beach, where 55 of the building’s 136 units were destroyed.
Miami-Dade Police Director Freddy Ramirez said that they have accounted for 53 people but are still working on confirming the whereabouts of the remaining residents.
Officials say that the number of unaccounted for people does not mean that they were all in the building at the time, as a number of the units are owned by vacationers.
“They are unaccounted for because they have not been heard from or have not called family or friends to say they are OK,” said Miami-Dade County Commissioner Sally Heyman.
A massive search-and-rescue operation was launched after the early morning collapse, which was caught happening in shocking video.
Firefighters used truck-mounted ladders to rescue people trapped on balconies and K9 teams have been scouring the rubble for signs of survivors.
Officials at Aventura Hospital said they had received three patients from the scene and that two were in critical condition.
“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 Surfside Mayor Charles 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.”
Officials in Paraguay have confirmed that among the missing are relatives of the country’s president Mario Abdo Benítez’s family.
Luis Pettengill and Sophia López Moreira, who is a sister of the first lady, Silvana López Moreira, are unaccounted for along with an employee and the couple’s three children.
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.
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.
A small fire appeared to break out in one section of the building as the search and rescue efforts continued on Thursday afternoon.