All beach front condos were built the same way then, and probably now.
Either the foundation is on bedrock, or they drove piling down to bedrock.
The only sinkholes I know about are fresh water sinkholes.
Sinkholes on the beach? First time I have heard about that in SE Florida.
Until proven otherwise, I will stick with my first instinct...
A large number of Jewish residents in the building...
Hamas (or fill in the blank) blew out several support columns in the underground parking lot.
The underground parking lot goes down at least two levels, and possibly three, so there would be no explosive sound outside. Just a sharp jolt, then, the building collapses.
Just on the news it’s a heavily orthodox Jewish area.