By Maria Medina

SAN FRANCISCO (KPIX) — Rescuers in Surfside, Florida worked throughout the night to locate dozens of people still unaccounted for after a condominium building collapsed without warning early Thursday morning.

“As the sun sets on the most tragic day this community can remember, we are working around the clock to search and rescue people in this rubble,” said Miami Dade mayor Daniella Levine-Cava.

Rescuers were racing against the clock to find survivors of the 12-story beachfront condo that crumbled around 1:30 a.m.

Former Miami-Dade fire chief Dave Downey said first responders were using dogs, cameras that fit into small spaces and listening devices to aid in their search.

As of Thursday night, at least 99 people were unaccounted for. One person was reported dead and at least 11 were injured.

Menlo Park Fire Protection District chief Harold Schapelhouman knows all too well the mission rescuers in Florida are on right now. He’s the task force leader of a California Search and Rescue team and was involved in locating victims of the Loma Prieta earthquake and Oklahoma City terrorist bombing.

“(In the) first 24 hours you’ve got a 90 percent chance of people that you recover who are salvageable, who will live,” Schapelhouman explained. “By the second day, based upon what happens to the human body after it’s been pinned in a certain area for a certain period of time, you’re looking at 36 percent. Day three: 30 percent. Day four: 18 percent. Day five: nine (percent).”

He said it’s a balance between working quickly but also safely.

“You have to be very careful with a building where you know two-thirds of it’s already collapsed, you’ve got a third that’s still there,” Schapelhouman said. “But, you know, will it collapse equally?”

“We are shoring up the structure on the inside as we continue to tunnel in to locate additional survivors,” said Miami-Dad Rescue fire chief Ray Jadallah.

It’s unknown what caused the 40-year-old building to crumble but researchers at Florida International University found it had been sinking at a rate of two millimeters a year for the past three decades. It was built on reclaimed wetlands.

“Which is pretty small but it was noticeable because the rest of the area was pretty stable,” said Shimon Wdowinski who was part of the study. “It’s not clear if the land was moving or the building was moving.”

The building was in the process of getting its 40-year recertification for electrical and structural safety.