The official death toll in the Surfside, Fla., building collapse rose to nine on Sunday, after search-and-rescue teams recovered four additional bodies overnight.

Miami-Dade Mayor Daniella Levine Cava confirmed the new death toll in a news conference Sunday. "As of today, one victim passed away in the hospital, and we've recovered eight more victims on-site, so I am confirming today that the death toll is at nine," Cava told reporters.

"We are making every effort to identify those others who have been recovered, and additionally, contacting their family members as soon as we are able," she continued. “My deepest condolences to the friends, the families, the communities of those who lost their lives.”

Late Saturday, four of the victims were identified: Stacie Dawn Fang, 54; Antonio Lozano, 83; Gladys Lozano, 79; and Manuel LaFont, 54.

Still, more than 150 people still remain unaccounted for – and as rescue operations stretch into a fourth day, authorities and loved ones fear the death toll could go much higher.

Cava said between six to eight rescue crews are “actively working” to search through the rubble around the clock, with “hundreds of others” on standby to rotate in as needed. The Army Corps of Engineers was also flown in to assist with operations. “We are not lacking any personnel,” Cava added. 

Emergency officials used heavy machinery to begin digging a trench into the wreckage last night, which Cava said allowed them to recover the four additional victims overnight. She described the trench, which currently runs about 40 feet deep, 20 feet wide, and 125 feet long, as “critical” to the continuation of rescue operations.

Teams are also working with engineers and sonar to make sure the rescuers are safe.

“We need to be sure that the pile does not fall on them. It does not fall on any possible survivors and we are diligently pursuing that as we do our work,” Cava said.

Search crews also began moving pieces of rubble to a nearby warehouse, where authorities said they will be investigated for forensic clues.

Miami-area officials also announced a 30-day audit of all buildings 40 years or older.

Appearing Sunday on NBC News’s “Meet the Press,” Cava pledged that city officials would be taking a “very aggressive” look at any potentially-vunerable buildings, though she added that the partial collapse of Champlain Towers South, “as far as we know and hope, is an anomaly.”

Appearing earlier Sunday on ABC News’s “This Week,” Surfside Mayor Charles Burkett said search-and-rescue teams had made “substantial” progress in their efforts, and said fires burning inside the rubble seemed to have diminished slightly overnight.

 “I was there this morning and took a walk around the site, and I did see a substantial difference from when I left at about 11 o’clock. So there is progress being made,” Burkett said. “It’s moving along.”

“We are working 24 hours a day, nonstop, nothing else on our mind, with the only objective of pulling their family members out of that rubble safely,” Burkett told host Jonathan Karl. “We’ve got world-class search and rescue people. We’ve got the dogs, we’ve got the cranes.”

“We are drowning in resources,” Burkett told reporters Sunday morning outside city hall. “We don’t have a resource problem, we have a luck problem.”

As search efforts continued Sunday, families of those missing voiced frustration with the slow pace of the operation.

But Earl Tilton, who runs a search-and-rescue consulting firm in North Carolina, told the AP that the rescuers in Miami-Dade County were doing an “outstanding job.” Rushing into the rubble without careful planning and execution would injure or kill rescuers and the people they are trying save, said Tilton, who runs Lodestar Professional Services in Hendersonville, N.C.

“I understand the families’ concerns on this. If it was my family member, I would want everyone in there pulling rubble away as fast as humanly possible,” Tilton said. “But moving the wrong piece of debris at the wrong time could cause it to fall on them and crush them.”

During past urban rescues, rescuers have found survivors as long as a week past the initial catastrophe, Tilton said.

This is a breaking news story. Earlier updates below.

Nearly three years before an oceanfront building collapsed near Miami, an engineering firm estimated that major repairs the building needed would cost more than $9 million, according to newly released emails.

The email from the firm of Morabito Consultants was among a series of documents released by the city of Surfside as rescue efforts continued at the site of the collapsed building, where more than 150 people remained unaccounted for. At least five people were killed in the collapse.

The release of the 2018 cost estimate followed the earlier publication of another document from the firm showing the ground-floor pool deck of the building was resting on a concrete slab that had “major structural damage” and needed to be extensively repaired. That report also uncovered “abundant cracking and spalling” of concrete columns, beams and walls in the parking garage.

The report did not warn of imminent danger from the damage, and it is unclear if any of the damage observed was responsible for the collapse of Champlain Towers South.

The cost estimate showed that repairs across the entire building would cost more than $9.1 million, with the cost of work at the garage, entrance and pool deck alone accounting for more than $3.8 million. The work had not been done by the time the building collapsed.

The earlier report said the waterproofing under the pool deck had failed and had been improperly laid flat instead of sloped, preventing water from draining off.

“The failed waterproofing is causing major structural damage to the concrete structural slab below these areas. Failure to replace the waterproofing in the near future will cause the extent of the concrete deterioration to expand exponentially,” the report said.

The firm recommended that the damaged slabs be replaced in what would be a major repair.

Some of the damage to the concrete in the parking garage was minor, while other columns had exposed and deteriorating rebar. It also noted that many of the building’s previous attempts to fix the columns and other damage with epoxy were marred by poor workmanship and were failing.

Beneath the pool deck “where the slab had been epoxy-injected, new cracks were radiating from the originally repaired cracks,” the report said.

These were all problems that should have been dealt with quickly, said Gregg Schlesinger, an attorney specializing in construction defects and a former construction project engineer.

“The building speaks to us. It is telling us we have a serious problem,” Schlesinger said in a telephone interview Saturday about the new documents. “They (building managers) kicked the can down the road. The maintenance was improper. These were all red flags that needed to be addressed. They weren’t.”

In a statement Saturday, Morabito Consultants confirmed its report “detailed significant cracks and breaks in the concrete, which required repairs to ensure the safety of the residents and the public.”

The firm said it was hired again in June 2020 by Champlain Towers South to begin the 40-year recertification process that would detail what work needed to be done.

“At the time of the building collapse, roof repairs were under way, but concrete restoration had not yet begun,” the statement said.

Abi Aghayere, a Drexel University engineering researcher, said the extent of the damage shown in the engineering report was notable. In addition to possible problems under the pool, he said several areas above the entrance drive showing signs of deterioration were worrisome and should have been repaired immediately.

“Were the supporting members deteriorated to the extent that a critical structural element or their connections failed leading to progressive collapse?” he wrote in an email to the AP after reviewing the report. “Were there other areas in the structure that were badly deteriorated and unnoticed?”

The building was in the midst of its 40-year recertification process, which requires detailed structural and electrical inspections. In an interview Friday, Surfside Mayor Charles Burkett said he wasn’t sure if the inspection had been completed, but he said it may contain vital clues.

“It should have been a very straightforward thing,” Burkett said. “Buildings in America do not just fall down like this. There is a reason. We need to find out what that reason is.”

The 12-story tower’s collapse Thursday morning has also raised questions over whether other similar buildings are in danger.

“This is a wake-up call for folks on the beach,” Schlesinger said. “The scary portion is the other buildings. You think this is unique? No.”

Details of the building’s 40-year recertification inspection will be made public once they are completed, Surfside Town Clerk Sandra McCready said in an email.

The collapse is already drawing lawsuits, including one filed hours after the collapse by attorney Brad Sohn against the condo’s homeowners association seeking damages for negligence and other reasons for all of the tower’s residents.

The association, the lawsuit contends, “could have prevented the collapse of Champlain Towers South through the exercise of ordinary care, safety measures and oversight.”

An attorney for the association, Ken Direktor, did not respond to an email requesting comment.