Cava said four bodies, as well as human remains, were found when workers dug a huge trench through the mountain of debris.

“We are making every effort to identify those others who have been recovered,” she said in a morning briefing.

Florida Governor Ron DeSantis said debris with “forensic value” is being taken to a large warehouse to be inspected as investigators seek to determine the cause of the collapse.

And Surfside mayor Charles Burkett said accommodation was being found for anyone wishing to evacuate the tower’s nearly identical “sister” building a block away, though no structural problems have yet been identified there.

Israeli and Mexican engineers and search-and-rescue specialists have joined an army of American workers at the site.

Teams in protective gear, backed by two huge cranes and aided by sniffer dogs, have been working nonstop in torrid heat and high humidity since the early-morning collapse.

Six to eight squads are “on the pile actually searching at any given time,” Cava said. The teams are able to work only a half-hour at a time before handing the job to the next crew.

“There is progress being made,” Burkett told ABC’s This Week. “We’ve got waves of search-and-rescue teams that are flowing over the site.

“We don’t have a resource problem,” he said. “We have a luck problem. We need to get more lucky right now.”

The 12-storey oceanfront Champlain Towers South collapsed in the middle of the night on Thursday as residents slept. Surveillance video of the collapse showed it coming down in just a few seconds.

The rescue operation has been agonisingly slow and painstaking, and fears of a much higher death toll are climbing with each passing hour – though rescuers have stressed that there may yet be survivors trapped inside the rubble.

Many members of the local Jewish community were among those affected by the tragedy in Surfside, near Miami Beach, and Israel had vowed to help with the agonising search.

“This is one of the best, if not the best, and the most experienced rescue teams, Israeli rescue teams,” Israeli diaspora affairs minister Nachman Shai said as the team arrived early on Sunday.

About half of Surfside’s population is Jewish, including many members of the Hasidic Chabad-Lubavitch movement, according to the Israeli media.

So far, four victims have been identified by local police: Gladys and Antonio Lozano, respectively aged 79 and 83; 54-year-old Stacie Fang, whose 15-year-old son was rescued from the debris on Thursday; and Manuel LaFont, also 54.

At least 18 Latin American nationals are among the missing – including Uruguayans, Argentines and Paraguayans. Canada has also said at least four of its citizens may be “affected,” without elaborating.

Late on Saturday, officials said they had been able to battle back a fire that for days had hampered their efforts.

Families of the missing have expressed mounting frustration and anger at the wait as concerns grown about the building’s condition before the collapse. Officials who spoke on Sunday repeatedly sought to reassure them that everything possible is being done.

02:15

Miami condo building collapse leaves at least one dead, nearly 100 unaccounted for

Miami condo building collapse leaves at least one dead, nearly 100 unaccounted for

“We’re moving as fast as we can, as hard as we can,” Miami-Dade fire chief Alan Cominsky told reporters.

Anger was fanned by news on Friday that an engineer’s survey of the building in 2018 had pointed to “major structural damage” to a concrete slab beneath a ground-level pool deck, as well as “abundant” damage inside the parking garage.

Authorities have stressed that the reason for the collapse could take months to determine.

US media have reported that one resident has already filed a class-action lawsuit against the building’s owners seeking compensation for victims.