Rescuers are still searching for survivors in the rubble of the collapsed Florida apartment tower, but pressure is building - from families of missing residents to the state's governor - for answers on how such a disaster could have occurred.

A wing of the oceanfront complex suddenly pancaked on itself around 1:30 a.m. (05:30 GMT) Thursday, with 55 apartments collapsing in a cloud of dust, leaving at least four dead and 159 people still missing on Friday.

"There are a lot of other people throughout this community and really throughout Florida who want to know, well, how could a building just collapse like that?" Governor Ron DeSantis said.

He called for a "timely" explanation, adding that families "have a right to know."

Mike Salberg, who is waiting for information on five missing family members, including his parents, echoed the sentiments.

"I want answers," said Salberg, adding that "The families are sidelined."

Latest with the search

"We have hope because that's what our search-and-rescue team tells us, that they have hope," Miami-Dade County Mayor Daniella Levine Cava told a news conference.

Aided by dogs, cameras, and sonar, the teams worked at the site on a rotation, with a limited number allowed at any one time to prevent further collapse, Levine Cava said.

Teams from Mexico and Israel arrived to help relieve the locally based crews, many of whom have also traveled to disaster sites around the world.

Atop the pile, some wielded hammers and picks looking for signs of life. Heavy equipment scraped away the top layer. Below ground, rescuers who entered through the parking garage risked their own lives searching for survivors, occasionally being hit by falling debris, officials said.

At least 27 people from Latin American countries, including Colombia, Cuba, Chile, Paraguay, Puerto Rico and Argentina, are among those reported missing by friends and family following the collapse, local newspaper Miami Herald said on Friday.

Read more: Survivor of Miami building collapse

Cause of the collapse uncertain

Completed in 1981, Champlain Towers South was due to be recertified this year in line with Miami-Dade county safety regulations, which require a review every 40 years, and roof work was ongoing as part of that process.

But county officials stressed there was no indication of a causal link between the refurbishment work and the collapse, which so far has a confirmed death toll of four.

Satellite data from the 1990s showed the building was sinking about one to three millimeters per year while surrounding buildings remained stable, said Florida International University professor Shimon Wdowinski.

"Either the building is settling into the soil or maybe there is some compromise with the structure, a compromise within the building. We cannot really say," he said in a telephone interview.

There was insufficient data to show whether the movement continued since then, Wdowinski said.

The other expert from the university, Atorod Azizinamini, chair of its civil and environmental engineering department, cautioned in an online video that it was too soon to speculate on a cause.

He said structural engineers would collect vast quantities of data on the building's design plans and construction methods, take samples of steel and concrete, look at signs of corrosion, examine the foundation for signs of settlement, and try to detect any unusual event before the collapse.

"It's going to take some time," said Azizinamini.

On Saturday, an emerging New York Times report said a consultant engineer had warned, three years before the deadly collapse, in a report that there was evidence of "major structural damage" to the concrete slab below the pool deck and abundant cracking and crumbling in the underground parking garage.

"Though some of this damage is minor, most of the concrete deterioration needs to be repaired in a timely fashion," consultant engineer Frank Morabito was quoted as writing about damage near the base of the 40-year-old building.

(With input from agencies)