By Gabriella Borter

SURFSIDE, Fla. (Reuters) -Rescue workers pulled a 10th body from the rubble of a collapsed Florida condominium on Monday, as officials vowed to keep searching for any possible survivors five days after the 12-story building fell without warning as residents slept.

Crews were using cranes, dogs and infrared scans as they looked for signs of life amid the ruins, hoping air pockets may have formed underneath the concrete that could be keeping some people alive.

“We’re going to continue and work ceaselessly to exhaust every possible options in our search,” Miami-Dade County Mayor Daniella Levine Cava told a news briefing.

The death toll appears certain to rise, and Levine Cava acknowledged the number of casualties is “fluid.” There are 151 people still unaccounted for.

The cause of the collapse at the Champlain Towers South in Surfside, near Miami, remains under investigation.

A 2018 engineer’s report found serious concrete deterioration in the underground parking garage as well as major damage in the concrete slab beneath the pool deck. The author, Frank Morabito, wrote the deterioration would “expand exponentially” if it was not repaired in the near future.

But Ross Prieto, then Surfside’s top building official, met residents the following month after reviewing the report and assured them the building was “in very good shape,” according to minutes of the meeting released by the town on Monday.

Reuters was unable to reach Prieto, who is no longer employed by Surfside. He told the Miami Herald newspaper he did not remember getting the report.

The engineer’s report was commissioned in advance of the condo seeking recertification, a required process for buildings that reach 40 years of age. The tower was constructed in 1981. An estimate prepared by Morabito Consultants in 2018 put the cost of repairs at $9.1 million, including electrical, plumbing and work on the façade.

After the meeting, Prieto emailed the town’s manager to say it “went very well. The response was very positive from everyone in the room. All main concerns over their forty year recertification process were addressed.”

Guillermo Olmedillo, Surfside’s town manager in 2018, told Reuters he did not recall hearing about any issues related to the tower based on the engineer’s report.

“The last thing I knew was that everything is OK, reported by the building official,” he said.

Gregg Schlesinger, a lawyer and former general contractor who specializes in construction-failure cases, said it was clear the deficiencies identified in the 2018 report were the main cause of the disaster.

But Donna DiMaggio Berger, a lawyer who works with the condo association, said the issues were typical for older buildings in the area and did not alarm board members, all of whom lived in the tower with their families.

Morabito Consultants was retained by the building in 2020 to prepare a 40-year building repair plan.

The firm said on Saturday that roof repairs were underway at the time of the collapse but concrete restoration had not yet started.

“We are deeply troubled by this building collapse and are working closely with the investigating authorities to understand why the structure failed,” it said.

Levine Cava vowed officials will “get to the bottom” of why the building collapsed but said the priority right now is searching for survivors.

‘TIME IS OF THE ESSENCE’

Miami-Dade Assistant Fire Chief Raide Jadallah said workers have found voids large enough to keep victims alive.

“Not to say that we have see anyone down there, but we’ve not gotten to the very bottom,” he said.

He said searchers have heard some sounds, such as tapping of scratching, though he acknowledged it could be metal shifting. But he emphasized that there is no set amount of time after which the rescue effort should cease.

The teams include experts sent by Israel and Mexico to assist in the search.

Some relatives of those missing have provided DNA samples to officials, and family members were permitted to pay a private visit to the site by special arrangement on Sunday, Levine Cava said.

The police have identified eight victims, including a couple married for nearly 60 years and a mother whose teenage son is one of the few known survivors.

At a makeshift memorial a block away, tributes to the victims and “missing” posters hung on a chain-link fence, with flowers and children’s toys strewn about.

Given the scores of those still missing, the disaster may end up one of the deadliest non-deliberate structural failures in U.S. history.

Ninety-eight people perished when the roof of the Knickerbocker Theatre in Washington, D.C., gave way from the weight of snow during a silent movie screening in January 1922. Two interior walkways collapsed into the lobby of the Hyatt Regency hotel in Kansas City, Missouri, during a dance party in July 1981, killing 114.

(Additional reporting by Brendan O’Brien, Brad Heath, Peter Szekely and Kanishka Singh; Writing by Joseph Ax; Editing by Angus MacSwan and Alistair Bell)