SURFSIDE, Fla. — The Fourth of July was marked with somber tones in South Florida, where a collapsed building has left at least 24 dead and more than 120 missing under rubble.

“July 4 is ordinarily a time to gather with our loved ones and to celebrate our freedom and our independence, and this year the holiday looks very different,” said Miami-Dade County Mayor Daniella Levine Cava.

“But through this grief ... and all of the other obstacles that have been thrown our way, a clear picture emerges of what it means to be American,” she said.

A vigil was planned Sunday night in Miami Beach for the victims of the fallen Champlain Towers South condominium complex in Surfside.

Neighboring Miami Beach typically hosts one of the region’s most spectacular fireworks displays, but officials canceled their show out of respect for the families.

Meanwhile, demolition specialists finished boring holes and began laying explosives in them as they prepared to bring down the precarious but still-standing portion of a collapsed South Florida condo building.

The work has suspended the search and rescue mission, but officials said it should eventually open up new areas for rescue teams to explore.

The decision to demolish the 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.

“Our top priority is that the building come down as soon as possible, no matter what time that occurs and as safely as possible,” Levine Cava said Sunday.

The drilling work was completed Sunday, and the remaining structure was scheduled to come down late Sunday or early Monday, barring any last-minute glitch such as someone entering the restricted zone around the building, Miami-Dade Assistant Fire Chief Raide Jadallah said.

That timeline drew applause from families eager for the search to restart. No one has been rescued alive since the first hours after the June 24 collapse.

The search at the building has been suspended since Saturday afternoon so workers could begin the drilling work.

Jadallah said the suspension was necessary because the drilling could cause the structure to fail, but a family member could be heard calling that news “devastating.”

Once the structure is demolished, the remnants will be removed immediately with the intent of giving rescuers access for the first time to parts of the garage area that are a focus of interest, Jadallah has said. That could give a clearer picture of voids that may exist in the rubble and could possibly harbor survivors.

Despite the dwindling chance that anyone remains alive in the rubble, officials have pledged to keep looking.

“There’s nobody in charge really talking about stopping this rescue effort,” Surfside Mayor Charles Burkett told CBS’ “Face the Nation.” “This rescue effort as far as I’m concerned will go on until everybody is pulled out of that debris.”

Officials began considering the demolition at Champlain Towers on Thursday when parts of the remaining building shifted, endangering rescuers and prompting a 15-hour suspension in their work.

Approaching Tropical Storm Elsa added urgency to those plans with forecasts suggesting there could be strong winds in the area by Monday. The latest forecasts have moved the storm westward, mostly sparing South Florida, but National Hurricane Center meteorologist Robert Molleda said the area could still feel effects.

“We’re expecting primarily tropical storm force gusts,” Molleda said, referring to gusts above 40 mph.

The detonation will aim to bring the remaining portion of the building straight down and toward the street side, away from the existing pile of debris, Jadallah said.

Search and rescue efforts should resume 15 to 60 minutes after the structure is brought down, Jadallah said.

The method of demolition is called “energetic felling,” which uses small detonation devices and relies on the force of gravity.

Levine Cava said that should bring the building down in place, containing the collapse to the immediate surroundings.

State officials said they hired the BG Group, a general contractor based in Delray, Florida, to lead the demolition.

It was not immediately known how the company was selected.

A spokesperson for the state’s Division of Emergency Management said the company is subcontracting with Maryland-based Controlled Demolition Inc., which experts say is among only a handful of companies in the U.S. that demolishes structures using explosives.

CDI is “probably one of the best” in the industry,” said Steve Schwartz, a member of the National Demolition Association’s board of directors.

No one will be allowed in the buildings to the immediate north and south of the collapsed structure.

Levine Cava advised other residents nearby to stay indoors during the demolition and close windows, doors and any other openings that could allow dust in.