One person is confirmed dead but more fatalities are expected as authorities warned the number of missing could increase from the current figure of “at least” 99.
Firefighters rescued 35 people from the Champlain Tower South building that collapsed in Surfside, a beachside town just 9.6km (6 miles) north of Miami.
Two people were pulled from the rubble, including a young boy, as early hope of finding more survivors faded with each passing hour. Eleven people were treated for injuries and four transported to local hospitals for further medical attention.
A state of emergency was declared as the Federal Emergency Management Agency (Fema) arrived to help search and recovery efforts, and to provide assistance and shelter to the 102 residents who have been accounted for. The 40-year-old 12-storey apartment building collapsed about 0130 local time [0530 GMT] on Thursday morning.
Miami-Dade Fire Rescue assistant chief of operations Ray Jadallah said that the sonar sound devices being used in various areas inside the rubble have detected signs that could potentially be from some of those still missing.
“We did receive sounds, not necessarily people talking, but sounds,” Mr Jadallah said.
“What sounds like people banging, well not people but sounds of a possibility of a banging. Short of that we haven’t heard any voices coming from the pile.”
Mr Jadallah said an underground parking garage had given firefighters access allowing them to tunnel to different floors in their search and rescue efforts.
From a maximum of 100 firefighters, about 60 to 70 at a time continued rescue efforts entirely beneath the surface from within the underground parking garage.
But the combination of sonar and dog crews searching the rubble had so far been unable to locate “voids” for crews to operate in and search.
“This process is slow and methodical,” he said, describing how a shift in the rubble caused a small fire that needed to be extinguished before resuming operations.
About 80 of the 130 apartment units were believed to be occupied at the time of the collapse, with 55 apartments that remained standing evacuated amid fears a second collapse could soon follow. While engineers were on-site to assess the damage and danger, work to determine the cause will not begin until rescue efforts end and Miami-Dade Fire Rescue hands over the scene to investigators.
As survivors at the family reunification centre in Miami spoke to the media, horrific details emerged of the chaos in the darkness of night as people fled the mountain of concrete and steel.
“Everybody was screaming and panicking … once you got down to the lobby … it was filled with nothing but dust and debris,” Aaron Miles told CNN. “It was awful. Kids, grownups screaming. Women and children crying. It was probably one of the worst experiences I’ve ever witnessed in my life.”
Jeff Pias, 60, told USA Today he was next door when he heard what sounded like a “huge tornado” before people started screaming for help. “I could see people on the balconies yelling, ‘Help me’,” he said.
Former Surfside vice mayor Barry Cohen, 63, told the newspaper he and his wife woke up from what sounded like a crack of lightning. They opened the door to find a gaping hole of rubble, “dust and smoke billowing around”.
Miami-Dade’s mayor, Daniella Levine Cava, said she signed an emergency order for Miami while Mr DeSantis signed the emergency declaration on Thursday evening.
A spokesperson for Mr DeSantis told The Independent the governor worked with Ms Cava and other local officials and were able to meet the immediate needs of search and rescue.
“With that, we will get the support from the federal agency Fema. The president has pledged that support and so shortly these orders will go forward and we will be able to bring in Fema federal assistance to this site and the families who are suffering,” the spokesperson said.
Earlier, Joe Biden said the White House was ready to move federal resources immediately and that Fema was already on site surveying the damage and the assistance needed.
“Fema is down there, taking a look at what’s needed, and including from everything from if the rest of those buildings have to be evacuated as well, finding housing for those people, making sure they have capacity to both have a place to, to shelter and food to eat, etcetera,” Mr Biden said.
“Whatever help you want the federal government can provide, we’re waiting, just ask us we’ll be there. We’ll be there,” he added.