The death toll rose to 16 in the condo building’s collapse, the Miami-Dade County mayor said.

The death toll in last week’s collapse of a condominium building in Sunrise, Fla., rose by four, to 16, on Wednesday, as the authorities said more bodies were recovered from the rubble overnight.

At a news conference on Wednesday, Mayor Danielle Levine Cava of Miami-Dade County said as many as 147 people remained missing, nearly a week after the desperate search for survivors began.

Earlier, a leader of an Israeli rescue team helping with the search of Champlain Towers South told CNN that the additional bodies had been recovered overnight as crews crawled through newly discovered tunnels in the debris.

“These tunnels that we found right now were almost the first to be big enough to enable people to stay between them,” Col. Golan Vach, the Israeli official, said. Colonel Vach added that he had hope that survivors might still be located, but that those prospects were dimming as the days elapsed.

Search teams said on Tuesday that they had removed more than three million pounds of debris from the wreckage since Thursday, when a section of the oceanfront complex caved in during the early-morning hours.

Yet as the pile of concrete, steel and personal effects slowly began to diminish, new warning signs pointing to the building’s critical failure began to emerge. A letter that the president of the condominium association wrote to residents in April publicly surfaced, revealing deep concerns about the building’s condition less than three months before it gave way.

While officials emphasized that they had adequate resources, they acknowledged that the demanding search and the unforgiving elements had placed a heavy burden on emergency responders.

On Tuesday evening, they said they had requested an additional urban search-and-rescue team from the federal government, which is sending President Biden and Jill Biden, the first lady, to Surfside on Thursday.

The extra search-and-rescue team would be placed on standby in case a tropical storm forms in the coming week. The officials said they were monitoring two weather systems in the Atlantic Ocean.

Miami-Dade County officials have declined to release a list of names of the nearly 150 people who remain unaccounted for.

Magaly Delgado, 80, who left Cuba in the early 1960s, fearing she would speak out against the revolution, was among them, said her daughter Magaly Ramsey. On Monday afternoon, she was allowed to visit the site of the tragedy, where she decided that her mother had not survived.

“I’m a very logical, tough woman,” said Ms. Ramsey, who had a question for a rescue official nearby. Can a body just disintegrate?

The answer, Ms. Ramsey recalled in an interview, was “yes.”

Flowers and messages of support on a makeshift memorial in Surfside, Fla., on Monday.Credit...Scott McIntyre for The New York Times

After another day of rescue workers digging through the rubble of Champlain Towers South, government officials announced on Tuesday that a 12th victim had been found, shrinking the list of people unaccounted for to 149.

But officials have not yet named those who are considered missing, forcing reporters and other observers to rely on the social media posts of family members or the laminated pictures tied to a fence at a nearby memorial site.

Mayor Daniella Levine Cava of Miami-Dade County has referred to concerns about confidentiality, and said on Tuesday that the authorities were in the process of auditing their list of missing people to get rid of duplicates.

When a relative or friend calls the county’s hotline to report someone who might be missing, state and local authorities pursue leads, review them and open a case. But some may have called about the same person, sometimes without apartment numbers. Some people may be listed with both their English and Hebrew names.

“We have people calling in from everywhere with hunches,” Ms. Levine Cava said.

The decision to not publicly release the list of the missing is a stark contrast compared to other disasters like the Paradise fire in Northern California in 2018. More than 1,000 people were initially listed as missing.

The sheriff there added every person who was described as missing in a 911 call and warned that the list would fluctuate. The hope was that people who checked in with the sheriff’s office would learn that someone was looking for them.

Stacie Fang, 54, was the first victim identified in the condo collapse. She was the mother of Jonah Handler, a 15-year-old boy who was pulled alive from the rubble in a dramatic rescue as he begged rescuers, “Please don’t leave me.”

Antonio Lozano, 83, and Gladys Lozano, 79, were confirmed dead by Mr. Lozano’s nephew, Phil Ferro, the chief meteorologist on WSVN Channel 7 in Miami. Mr. Ferro wrote on Instagram: “They were such beautiful people. May they rest in peace.”

Luis Andres Bermudez, 26, lived with his mother, Ana Ortiz, 46, and stepfather, Frank Kleiman, 55. Mr. Bermudez’s father confirmed his son’s death on social media, writing in Spanish: “My Luiyo. You gave me everything … I will miss you all of my life. We’ll see each other soon. I will never leave you alone.”

Manuel LaFont, 54, was a businessman who worked with Latin American companies. His former wife, Adriana LaFont, described him as “the best dad.” Mr. LaFont’s son, 10, and daughter, 13, were with Ms. LaFont when the building collapsed.

Leon Oliwkowicz, 80, and Cristina Beatriz Elvira, 74, were from Venezuela and had recently moved to Surfside, according to Chabadinfo.com, which said they were active in the Orthodox Jewish community in greater Chicago, where one of their daughters lives.

Marcus Joseph Guara, 52, lived with his wife, Ana, and their two daughters, Lucia and Emma, all of whom remain missing. He was remembered as a kind and generous man, a godfather to twins and a fan of hard rock music.

Hilda Noriega, 92, a longtime resident of Champlain Towers South who enjoyed traveling and whose family described her “unconditional love.” Hours before the collapse, she attended a celebration with relatives.

Also killed in the collapse was Michael David Altman, 50

— The New York Times

Near the site of the Champlain Towers South collapse in Surfside, Fla., on Monday.Credit...Scott McIntyre for The New York Times

As crews sift through the rubble of the collapsed condominium building near Miami in hopes of rescuing more residents, another effort is underway to support the survivors who made it out of the apartment building.

Thousands of dollars have poured in to Surfside, Fla., to support not only the families of those who are missing in the wreckage of Champlain Towers South, but the survivors who are now grappling with the loss of their homes and most, if not all, of their possessions. As of Wednesday morning, the Chesed Fund, run by the Shul of Bal Harbour, had raised more than $1.2 million.

“Most of the people I met left with the shirts on their backs,” said Michael Capponi, the founder of Global Empowerment Mission, a nonprofit humanitarian organization that has partnered with BStrong, a foundation supported by Bethenny Frankel, the entrepreneur and reality television star, to help support the survivors of the apartment collapse.

“You’re dealing with people who have worked their whole lives to pay a mortgage,” he added. “Now it’s gone.”

In a warehouse in Doral, Fla., he and volunteers put together an assembly line of cardboard boxes: kits with toothbrushes and toothpaste, phone chargers, blankets, pillows, shaving cream, vitamins, carefully wrapped in branded packaging and sleek fabric cases to make it easy to transport. The organization also aims to distribute $180,000 in gift cards by the end of the week, to help families buy food and supplies while they figure out their next steps.

The next challenge has been temporary housing: while hotels have opened rooms to help support reunification centers, Mr. Capponi and other organizations are working to find temporary apartments — ideally already furnished and open for at least a month — that will allow the survivors to have their own home outside of a hotel. Some need to be near a temple, others wish to remain close to the collapsed building as they wait anxiously for news about their neighbors, friends and loved ones.

Less than three months before the collapse of the Champlain Towers South condo in Surfside, Fla., the president of the condominium association warned in a letter that the damage in the building had “gotten significantly worse” since it was highlighted in a 2018 inspection.

The letter was written to residents by Jean Wodnicki, president of the association’s board of directors, explaining why a list of extensive construction projects were worth a $15 million special assessment that residents were being asked to pay.

Along with the 2018 inspection, which warned of “major structural damage,” the letter, a copy of which The New York Times obtained, adds to a growing body of evidence that engineers had raised alarms about serious flaws in the building months and even years before the catastrophic building failure, which killed 12 people and left 149 unaccounted for.

Ms. Wodnicki could not immediately be reached for comment.

That 2018 inspection warned that concrete damage would “multiply exponentially” in the coming years, Ms. Wodnicki wrote in the letter, which was earlier reported by USA Today and The Wall Street Journal. The engineer who prepared that initial report, Frank Morabito, carried out “a much more detailed survey of the property” and found signs that this acceleration was indeed already happening. “When you can visually see the concrete spalling (cracking), that means that the rebar holding it together is rusting and deteriorating beneath the surface,” Ms. Wodnicki wrote.

She explained that these signs of growing damage were why the estimated costs of repair had jumped by some 60 percent since that 2018 inspection. “The concrete deterioration is accelerating. The roof situation got much worse,” she wrote, adding, “New problems have been identified.”

“A lot of this work could have been done or planned for in years gone by,” she wrote in the letter. “But this is where we are now.”

Sharon Schechter, a renter of an 11th-floor unit in the condo tower, told CNN on Tuesday night that cracks in the building and the presence of water in the parking garage had been conspicuous. She said that she was in bed when she felt something like an earthquake, and that when she looked out the glass doors of her terrace, the landscape was unrecognizable.

“I saw nothing, and I’m saying to myself, ‘Where is my building?’” she said. “I thought I was dreaming. I thought I was in a nightmare.”

Coco remained inside when her owners evacuated the intact part of the building.

Above the rubble in Surfside, Fla., on the still-standing fourth-floor balcony of the collapsed condo building, firefighters this week left food and water for a cat named Coco.

A Miami city commissioner, Ken Russell, had initiated the search for pets left in the building when he heard from someone who is friends with Coco’s owners, who safely evacuated on Thursday morning.

When Coco’s owners, an 89-year-old woman and her daughter, were led out of the building by firefighters, their dog, Rigatoni, followed. But Coco remained inside the apartment.

“Clearly the priority is loss of human life and rescuing people,” Mr. Russell said. But he added that those who made it out of the building safely were distressed after losing their possessions and their pets, and that rescue workers could assist “them with reunification or at least giving them the peace of mind that we are trying to help at least feed their animals.”

Chief Alan Cominsky of Miami-Dade Fire Rescue said on Tuesday that his team did not find any indication of more pets still in the building.

The organization Friends of Miami Animals set up a hotline on Tuesday for residents of the collapsed building looking for assistance in rescuing pets. The hotline number is 833-366-2642.

— Sophie Kasakove