The increase in the death toll by one underscored the slow and painstaking search process more than two days after part of the 12-story oceanfront building in Surfside, near Miami Beach, pancaked into a mountain of debris as residents slept inside.

"Today our search and rescue teams found another body in the rubble and as well our search has revealed some human remains," Miami-Dade County mayor Daniella Levine Cava told reporters Saturday evening.

With the identification of three previously recovered bodies and notification of next of kin, "it means that the unaccounted is now gone down to 156, confirmed deaths are now at a total of five," she said.

Rescuers were able to battle back a fire that hampered their efforts earlier in the day, and workers had dug a trench through the debris to control the "very deep" blaze.

"We don't have a resource problem here, we have a luck problem," said Surfside Mayor Charles Burkett.

"The issue is we've been fighting the elements, we've been fighting the fire, but we have one objective. And that is to bring those people out of the rubble safely and return them to their families."

The passage of time with no further survivors being found raised fears of a much higher death toll as rescuers sift through the debris with heavy machinery and sniffer dogs, and as increasingly frustrated families continued their agonizing wait.

"We have a friend who got out of the building with her husband," Gina Berlin, 54, who lives in the neighborhood, told AFP. "She is still traumatized... And I am still in shock."

At a makeshift memorial on a nearby street, well-wishers piled flowers and lit candles, while family members posted dozens of pictures of missing persons on a chain-link fence.

Two big cranes on Saturday continued shifting debris as the acrid smell of burnt rubber and melting plastic hung in the baking Florida heat.

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