Updated

A massive rescue effort is underway Friday morning in Surfside, Florida, in response to the partial building collapse that killed at least four people and resulted in at least 159 people being unaccounted for.

Miami-Dade County Mayor Daniella Levine Cava said Friday that three bodies were pulled from the rubble overnight, bringing the total death toll to four. Cava said so far foul play does not appear to have been a factor, but said investigators are not ruling anything out. 

Speaking to reporters on Friday, Cava said rescuers were continuing their efforts despite the high risk and said they "will continue search and rescue because we still have hope that we will find people alive." 

"This work is being done at extreme risk to these individuals. Debris is falling on them as they do their work," Cava said. "They are proceeding because they are so motivated and they are taking extraordinary risk on the scene every day."

She said rescuers were using sonar technology, K-9s, cameras, "everything possible."

Miami-Dade Fire Chief Ray Jadallah said rescuers heard sonar-detected sounds "throughout the night."

When asked about tapping sounds reported to have been picked up by the sonar technology, Jadallah said that it's "not necessarily tapping, it's just sounds ... it could be various things. It could be just steel twisting, it could be debris raining down. But not specifically sounds of tapping or sounds of human voice."

"Every time that we hear a sound, we concentrate in that area. So, we send additional teams, utilizing the devices, utilizing K-9, utilizing personnel. As we continue to hear those sounds we concentrate in those areas."

The Miami-Dade Medical Examiner's Office identified its first victim of Thursday morning's tragedy as 54-year-old Stacie Fang, local news station WSVN-TV reported. Fang was reportedly taken to an area hospital after being recovered early Thursday, and died of blunt force injures.

A spokesperson for the medical examiner's office did not immediately respond to Fox News' request seeking confirmation.

According to WSVN, Fang had been staying on the 10th floor of the building. Her son was also rescued after the collapse, according to the report.

"There are no words to describe the tragic loss of our beloved Stacie," reads part of a family statement obtained by the news station.

Surfside Mayor Charles Burkett said in a previous interview that the building was "literally pancaked."

"It has gone down, and I mean there’s just feet in between stories where there was 10 feet," he said. "That is heartbreaking because it doesn’t mean to me that we’re gonna be as successful as we would want to be to find people alive."

The Miami-Dade Fire Rescue took to Twitter to post footage of rescuers working in the basement parking garage at the Champlain Towers. The crew is standing in knee-high water using a power drill to break through a wall. The ceiling appears to be folded in and is being supported by lifts, which underscored the risk that these rescue teams face while trying to find survivors.

"Firefighters continue working on locating possible victims, while dealing with heavy damage and changing conditions in the parking garage," the tweet read.

The weather outside was also not cooperating. There were storms in the area last night and reports of lightning. Local 10 reported that the scene was "dark, cloudy and windy. A fog of dust rose from the concrete."

A spokeswoman from Miami Dade said structural engineers were on-site and monitoring the stability of the part of the building that is still standing. The report said teams of 10 to 12 were carrying out operations "underneath the rubble." A small fire also broke out at the scene that was extinguished, reports said.

Jimmy Patronis, the state’s fire marshal, told reporters that rescue crews will not stop "just because of nightfall. They just may have a different path they pursue."

Patronis said he was deeply moved by the image of a bunk bed near the now-exposed top of the building.

"Somebody was probably sleeping in it," he said. "There’s all those what-ifs."

President Biden on Friday ordered federal assistance to support the massive response in South Florida after a 12-story building partially collapsed, killing at least one person and trapping others.

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"The President's action authorizes the Department of Homeland Security, Federal Emergency Management Agency (FEMA), to coordinate all disaster relief efforts,'' the White House said.