By Gabriella Borter

SURFSIDE, Fla. (Reuters) -Search-and-rescue operations stretched into a sixth day on Tuesday at the site of an oceanside Florida condominium complex that partially collapsed, although with no survivors found since last week hopes are dim for the 150 people still missing.

Miami-Dade County Mayor Daniella Levine Cava told reporters that no bodies had been recovered from the rubble since Monday, keeping the official death toll at 11.

What caused a major section of the 40-year-old high-rise to crumble into a heap remains under investigation. Initial attention has focused on structural deficiencies described in a 2018 engineer’s report.

In April 2021, the condo association president warned residents that concrete damage had “gotten significantly worse” along with roof damage, and urged them to pay some $15 million in assessments needed to make repairs, media reported.

Authorities on Tuesday held out the possibility that survivors might yet be found in the pile of concrete and twisted metal left when nearly half of the tower abruptly caved in on itself.

“The way I look at it as an old Navy guy is that when somebody is missing in the military, you’re missing until you’re found, and we don’t stop the search,” said Florida Governor Ron DeSantis. “Those first-responders are breaking their back, trying to find anybody they can.”

Officials said late on Monday that emergency teams were still treating the round-the-clock operation – which has employed dog teams, cranes and infrared scanners – as a search-and-rescue effort.

But no one has been extricated alive from the ruins of the oceanfront Champlain Towers South condo in Surfside, adjacent to Miami Beach, since a few hours after one side of the high-rise collapsed early Thursday morning as residents slept.

Fire officials have spoken of detecting faint sounds from inside the rubble pile and finding voids deep in the debris large enough to possibly sustain life.

“Not to say that we have seen anyone down there, but we’ve not gotten to the very bottom,” Miami-Dade Assistant Fire Chief Raide Jadallah told reporters on Monday.

President Joe Biden and his wife Jill Biden will visit Surfside on Thursday, the White House said.

“They want to thank the heroic first responders, search-and-rescue teams and everyone who has been working tirelessly around the clock, and meet with the families who have been forced to endure this terrible tragedy,” White House spokeswoman Jen Psaki told reporters.

The disaster has led officials in nearby areas scrambling to check the safety of buildings.

Miami Beach, just to the south of Surfside, has ordered a “walkthrough visual” inspection of about 500 multi-family commercial units over the next week, Mayor Dan Gelber said.

“But at the same time we are going to require within probably three weeks, all of these buildings in the recertification process to come up with an updated report,” Gelber told CNN.

The tragedy may end up ranking as the greatest loss of life from an accidental building collapse in U.S. history.

Crowds of rescue workers were standing on top of the debris pile on Tuesday morning, sifting through the rubble. Scattered thunderstorms are expected on Tuesday, potentially slowing search efforts.

A makeshift memorial a block from the site held bouquets of fresh hydrangeas tucked into a chain-link fence. A poster board with hearts had a message for the first responders: “Thank you for looking for my grandmother.”

ENGINEER’S REPORT

The 2018 engineer’s report warned of “major structural damage” to the concrete slab beneath the pool deck and concrete deterioration, including exposed rebar, in the underground parking garage. The report’s author, Frank Morabito, wrote that the deterioration would “expand exponentially” if not repaired.

In April 2021, the condo association president informed residents that the concrete damage had “gotten significantly worse,” along with roof damage, and urged them to pay around $15 million in assessments needed to make repairs, according to a letter obtained by the Wall Street Journal and USA Today and seen by Reuters.

“It’s all starting to come together now, because like I’ve said all along, there was something very, very wrong at this building,” Surfside Mayor Charles Burkett told CNN on Tuesday when asked about the letter. “Buildings in America just don’t fall down like this.”

Burkett said the condominium association officials probably did not grasp the “intensity” of the issue. “Obviously, that was a fatal mistake,” he said.

A lawyer who works with the association, Donna DiMaggio Berger, previously said the issues outlined in the 2018 report were typical for older buildings in the area.

Ross Prieto, then Surfside’s top building official, met residents weeks after the report was produced and assured them the building was “in very good shape,” according to minutes of the meeting released 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.

(Reporting by Gabriella Borter in Surfside, Florida; Additional reporting by Brendan O’Brien, Brad Heath, Peter Szekely, Kanishka Singh and Dan Whitcomb; Writing by Joseph Ax and Alistair Bell; editing by Jonathan Oatis and Rosalba O’Brien)