The death toll from a partial building collapse in the US state of Florida rose to four on Friday morning as authorities continue to search through sprawling debris in the city of Surfside.

Miami-Dade County Mayor Daniella Levine Cava said 159 people remain unaccounted for as search and rescue teams sift through the shifting concrete and metal remnants of the 12-story Champlain Towers South. In all, 120 people have been accounted for, she said.

Cava described the figures as being “very fluid,” noting first responders worked through the night both above ground and below in an underground parking garage that is being used to access the debris.

Surfside Mayor Charles Burkett voiced skepticism on Thursday on survivors being pulled from the debris alive due to the nature of the early morning collapse, which he described as the building being “pancaked” with individual floors falling on top of one another.

Just after midnight, US President Joe Biden declared a state of emergency, and authorized federal assistance to aid state and local efforts.

Cava thanked Biden for the action, saying it will assist in recovery efforts and aid for families.

One hundred and thirty fire fighters are assisting in the operation, sifting through the debris and fighting a fire that continues to reignite, officials said.

“This work is being done at extreme risk to these individuals. Debris is falling on them as they do their work. We have structural engineers on site to assure that they will not be injured, but they are proceeding because they are so motivated and they are taking extraordinary risk on the scene every day,” said Cava.

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