SURFSIDE, Fla. (NewsNation Now) — Rescuers searched through fresh rubble Monday after the last of the collapsed Florida condo building was demolished, which allowed crews into previously inaccessible places, including bedrooms where people were believed to be sleeping at the time of the disaster, officials said.

But they faced a new challenge from thunderstorms that hit the area as Tropical Storm Elsa approached the state.

Four more victims were discovered in the new pile, Miami-Dade Assistant Fire Chief Raide Jadallah told family members, raising the death toll to 28 people. Another 117 people remain unaccounted for.

The demolition late Sunday was crucial to the search-and-rescue effort, officials said, and raised the prospect that crews could increase both the pace of their work and the number of searchers at the site, although the chance of finding survivors 12 days after the June 24 collapse has diminished.

“We know that with every day that goes by, it is harder to see a miracle happening,” said Maggie Castro, a firefighter and paramedic with the Miami-Dade Fire Rescue who briefs families daily.

Teams had been unable to access areas closest to the remaining structure because of its instability, Miami-Dade County Mayor Daniella Levine Cava said.

“Truly we could not continue without bringing this building down,” she said at a news conference.

During the demolition, a loud rat-at-tat of explosions echoed from the structure. Then the building began to fall, one floor after another, cascading into an explosion of dust. Plumes billowed into the air, as crowds watched the scene from afar.

Crews could be seen climbing a mound of debris at the site Monday alongside a piece of heavy equipment that was picking up rubble. Jadallah said rescuers focused on a stairwell section, but inclement weather hampered the search, particularly in a garage area that was filling with water. Crews had to pump out water.

The latest forecasts showed the storm moving westward, mostly sparing South Florida, but the area near the collapsed building experienced thunderstorms, and the National Weather Service issued a severe thunderstorm warning for Miami Beach, which is just south of Surfside.

Jadallah said rescuers planned to push through.

“Now that we don’t have an issue with the building, the only time that we’re stopping is lightning,” he said.

The decision to demolish the remnants of the Surfside building came after concerns mounted that the damaged structure was at risk of falling, endangering the crews below and preventing them from operating in some areas. Parts of the remaining building shifted on Thursday, prompting a 15-hour suspension in the work.

Authorities had gone door-to-door to advise nearby residents of the timing of the demolition, and to ask them to keep windows closed. They were told to stay inside until two hours after the blast to avoid the dust raised by the implosion.

The method used for Sunday night’s demolition is called “energetic felling,” which uses small detonation devices and relies on the force of gravity. The goal was to bring the building down in place, containing the collapse to the immediate surroundings.

Officials used tarps to visually mark the search area, in case new debris scattered unexpectedly.