At least one person has been killed and 99 are still missing, officials say.
As families desperately wait for news, search teams have been working around the clock and have reported hearing people banging beneath the debris.
What caused the 40-year-old building to collapse early on Thursday morning remains unclear.
At least 102 people have now been accounted for, but it is uncertain how many were in the building when it came down. Dozens of survivors have been pulled out of the rubble.
President Joe Biden has approved an emergency declaration for Florida, meaning the Federal Emergency Management Agency will help state agencies with the relief effort.
As night fell, hundreds of rescuers were using sonar cameras and specially trained dogs as they scoured the rubble for survivors. Teams were tunnelling from an underground car park below the building in an effort to reach victims.
“Fire and rescue are in there with their search team, with their dogs,” Miami-Dade Police Director Freddy Ramirez told reporters.