• Eighteen people are dead and 145 remain missing nearly one week into a search-and-rescue operation amid the rubble of a collapsed 12-story condominium complex in Surfside, Florida.
• The likelihood of finding more living people in the wreckage continued to diminish as first responders' efforts stretched into their seventh day.
• President Joe Biden and first lady Jill Biden will travel to the site on Thursday, White House press secretary Jen Psaki said this week.

The death toll in the collapse of a Florida condominium building rose to 18, with 145 people still unaccounted for, Miami-Dade County Mayor Daniella Levine Cava said at a press conference Wednesday afternoon.

Two of the confirmed deaths are children, ages four and ten, according to Levine Cava.

"Our detectives have been working around the clock to reach every single person who we have been told may be missing," Levine Cava told reporters.

The likelihood of finding more people alive in the wreckage continued to diminish as first responders' painstaking search-and-rescue efforts enter day seven. No survivors have been pulled from the site since a few hours after nearly half of Champlain Towers South, a 40-year-old, 136-unit condo building, caved in last Thursday.

"Please join me in continuing to pray for those who've lost their lives in this unthinkable tragedy, and all of their families who are grieving," Levine Cava said at the press conference. 

Levine Cava announced that the National Hurricane Center released projections for a possible category 5 tropical cyclone moving northwest across the Caribbean Sea, adding that authorities are monitoring the storm closely.

While it is too soon to determine the potential impacts of the storm on the state, Florida Division of Emergency Management Director Kevin Guthrie outlined contingency plans for such severe weather that could further delay search-and-rescue operations at the site. 

The division has asked the federal government for an additional rescue team to pursue the search through the rubble, which would allow other teams that have been working at the site to rotate out, according to Guthrie. He added that the division is developing a system that would provide facility relocation assistance, communications and "backup plans" for responding to both the building collapse and a tropical storm. 

"The state emergency response team is extremely experienced in managing multiple disasters at one time," Guthrie told reporters.

The specific cause of the cave-in is still unknown.

In the wake of the collapse, Surfside authorities released a 2018 survey report in which an engineer warned that the building had shown signs of "major structural damage," noting issues with waterproofing beneath the pool and cracking in the underground parking garage. 

A letter from the Champlain Towers South Board President Jean Wodnicki two months before the collapse also warned about the building's structural issues, pointing to accelerating "concrete deterioration" that had worsened since the 2018 report.

Levine Cava said her team is collaborating with subject matter experts to launch an investigation into the collapse and develop recommendations for building processes at the local level to "ensure that this tragedy can never happen again."

She also expressed her support for State Attorney Katherine Fernandez Rundle's plans to pursue a grand jury investigation.

"I plan to request that our Grand Jury look at what steps we can take to safeguard our residents without jeopardizing any scientific, public safety, or potential criminal investigations," Fernandez Rundle said in a statement Tuesday, noting that the grand jury helped issue a report during the aftermath of Hurricane Andrew in 1992. 

The National Institute of Standards and Technology, or NIST, director James Olthoff also announced the establishment of a technical team that will investigate the collapse and develop improved building codes without interrupting ongoing search-and-rescue operations. 

Under the National Construction Safety Act of 2002, the team of NIST staff and outside experts is permitted to collect evidence from the site, issue subpoenas and hold hearings to determine the technical cause of the collapse. 

"We are going in with an open mind," Judith Mitrani-Reiser, the associate chief of the Materials and Structural Systems Division at NIST, told reporters. "In any building collapse, we would want to understand how the building was designed, how it was constructed, modified and maintained." 

Levin Cava also told reporters that the Department of Regulatory and Economic Resources has moved forward with 30-day audit of all residential properties above four stories that are 40 years old or older and "have not completed the process to identify and address any issues."

The county is collaborating with partners in 34 cities of Miami-Dade County to conduct reviews on buildings that meet this criteria, Levine Cava said Wednesday.

"We are going to get inputs and develop a set of recommendations for changes that need to be made here in the building process at the local level to ensure that this tragedy can never ever happen again," Levine Cava told reporters.

Surfside Mayor Charles Burkett pointed to the Champlain Towers North, the sister property of the collapsed condo building, noting that residents and an engineer the city hired have expressed "serious concerns" about its safety.

Burkett told reporters that the city and NIST are currently developing a plan to ensure that residents are safe and have alternative housing options.

Guthrie also announced updates regarding resources for individuals impacted by the collapse and their families, noting that the Florida Finance Corporation has found more than 120 multifamily rental developments to serve as emergency housing for displaced individuals.

The Florida Housing Finance Corporation has also requested that the Department of Housing and Urban Development waive income limitations to allow families to reside in any vacant properties funded by the HOME Investment Partnerships Program, according to Guthrie. 

The Office of Emergency Management division director Charles Cyrille also announced expanded operations at the Family Assistance Center, which offers mental health, grief counseling, financial, lodging and travel assistance, among others, to victims' families. Twenty-six organizations are currently working with the center to provide support.

President Joe Biden and first lady Jill Biden will travel to the site on Thursday, White House press secretary Jen Psaki said earlier this week.

The Bidens plan to personally thank first responders, rescue teams and "everyone who's been working tirelessly around the clock," Psaki told reporters Tuesday.

Biden supports a federal probe into the matter, Psaki said this week.

"We're very grateful that the President is coming," said Miami-Dade Police Director Alfredo Ramirez III. "He's been showing support for this community since the beginning."

On Saturday I announced that a 30-day building audit would begin immediately for all residential properties 5 stories+ at the recertification point (40 years or older) that have not completed the process, to identify and swiftly address any issues.

— Daniella Levine Cava (@MayorDaniella) June 28, 2021

—Reuters contributed to this report.