First responders and rescue crews racing to uncover any hint of life among the debris of a partially collapsed condo tower in Florida pulled another three bodies from the wreckage overnight, bringing the death toll to four.

Miami-Dade Mayor Daniella Levine Cava revealed the grim news in a Friday morning news conference. She called the update “devastating news for families waiting for any hope for survival,” in an interview with ABC News, during which she also said she is “very hopeful” others can still be rescued.

At least 159 others remained unaccounted in wake of the tragedy early Friday morning, despite crews working through the night, without a break. The figure is significantly higher than the previously estimated 99 missing.

Residents inside the 12-story oceanfront residence jumped from their beds around 1:30 a.m., when the building began to tremble. What they thought was severe weather, a brutal thunderstorm perhaps, turned out to be their home falling to pieces. About 55 units were affected in the partial collapse, with the bedrooms and kitchens of those apartments left still standing totally exposed after the wall fell to pieces.

Air conditioning units and wires were left dangling along what remained of the building while the region nearby was left coated with rubble and dust.

Cava noted the numbers of those unaccounted for are “fluid” because it’s still unclear who was inside of the building when it went down.

State Chief Financial Officer Jimmy Patronis, who also serves as the state fire marshal, told CNN the rescue mission would continue with teams from Naples and Orlando coming to relieve the Miami-Dade responders, who have been combing through the rubble for more than 24 hours straight. He added that rescue teams were using all means necessary to reach any potential survivors, adding that they spent the night sawing through concrete and scouring the rubble with sonar and using specially trained dogs.

“We’re not giving up,” Surfside Mayor Charles Burkett told the news station. “That is the one thing we’re not doing. We’re searching 24 hours a day, and we’re pulling as many people out as we can. That’s the whole goal right now. Nothing else matters.”

First responders rescued 35 people from the building in Surfside, a beach town just six miles north of Miami, including a young boy who was trapped among the debris. Search teams spotted his wiggling fingers beneath the wreck and were able to carry him to safety. No other survivors have been recovered since early Thursday.

Eleven of those rescued were treated for injuries at the scene and four were transported to local hospitals for further medical attention.

What triggered the collapse is still unknown.