The death toll for the Surfside, Florida, building collapse rose to 12, Miami-Dade County Mayor Daniella Levine Cava said Tuesday.

The total number of people unaccounted for is now 149 and the number of people accounted for is 125, Levine Cava said during the latest update on search and rescue efforts.

Still, some, including the commander of an Israeli team helping to search the rubble, remain hopeful.

Col. Golan Vach, commander of the Israeli National Rescue Unit, said that while this is the most difficult site he has ever worked, his team found new spaces in the rubble to search Monday and Tuesday.

“So there is still hope,” Vach told CNN’s Wolf Blitzer. “Until one week, I have a solid hope that we will find someone. After one week, it’s minor.”

The building partially collapsed in the middle of the night last Thursday.

Vach’s team comprises 15 engineers, search and rescue experts and others. He said he’s never seen a collapse like this one.

“This building collapsed very, very badly, if I can use this word, because it collapsed into itself,” he said. “And the bedrooms that we are looking for, because the people (slept) in the bedrooms, are under 4 or 5 meters (13 to 16 feet) of concrete.”

Rescuers will continue to consider the unaccounted-for as “missing until they are found,” Gov. Ron DeSantis said in a news conference late Tuesday morning.

“Nobody is giving up hope here. Nobody is stopping,” Surfiside Mayor Charles Burkett said at the same news conference.

Officials acknowledged that conditions at the site are challenging for emergency workers. Burkett told CNN’s John Berman earlier on Tuesday that debris had fallen overnight Monday into Tuesday from portions of the building that remain standing.

Additionally, workers are steering clear of a “45-foot area next to the building” because of concerns about overhanging debris from the standing portion, Miami-Dade Fire Chief Alan Cominsky said Tuesday.

More than 3 million pounds of concrete have been removed during the rescue operation, Cominsky said.

A six-person team of federal officials from the National Institute of Standards and Technology — consisting of scientists, structural engineers and a geotechnical engineer — is conducting a preliminary investigation of the collapsed building’s materials, history and applicable building codes at the time the condo was built, the ground surrounding the building and numerous other factors, according to an agency official.

The White House announced President Joe Biden planned to be in Surfside on Thursday to visit with victims’ families and first responders.