The slabs of concrete easily weigh tons apiece. Workers are typically well aware of the risks when they're being positioned, and when something goes wrong, it's tough to survive.
"Any slight deviation in the alignment will cause a catastrophic failure," Brizuela said. "They had no chance, the guys that were underneath."
Joe White, an owner of Carl Walker Construction Inc., a Pittsburgh company specializing in parking garages, said he suspected the problem may have been there were too few welders to secure the concrete pieces together. Left unsecured, anything from a gust of wind to a tap from a crane could send a slab crashing over, White said.
"All they have to do is tap that thing and it just knocks that whole thing straight to the ground," he said.
Authorities have not yet identified any cause in the accident. Byrne said there was "no warning whatsoever."
Ground was broken on the $22.5 million project in February, and the 1,855-space garage was to be finished in December, according to Ajax's website. The first floor was to have classroom and office space. The structure is next to the main office building at the 8,000-student college and nestled among other campus buildings.
No students were in the accident area because the garage was under construction. The campus was evacuated and closed for the rest of the week. Officials said there was no visible damage to other buildings, but even a hairline fracture could compromise safety.
"Very concerning to us was that this facility was about to open," said Juan Mendieta, a spokesman for Miami Dade College. "Had this collapse happened just a couple of months from now, it would have been a totally different story. So for that reason, we're not going to leave a stone unturned."
Associated Press writer Freida Frisaro contributed to this report.