Demolition specialists finished boring holes and began laying explosives in them Sunday as they prepared to bring down the precarious but still-standing portion of a collapsed South Florida condo building, a top Miami-Dade fire official said. 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 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.

“Our top priority is that the building come down as soon as possible, no matter what time that occurs and as safely as possible,” Miami-Dade County Mayor Daniella Levine Cava told a news conference Sunday. “Bringing down this building in a controlled manner is critical to expanding the scope of our search-and-rescue effort.”

The drilling work was completed Sunday, and the remaining structure was scheduled to come down between 10 p.m. Sunday and 3 a.m. Monday, barring any last-minute glitch such as someone entering the restricted zone around the building, Miami-Dade Assistant Fire Chief Raide Jadallah told relatives of those missing in the collapse.

Up to 210 rescuers will be poised to restart the search as soon as the site is declared safe after the blast, he said. Rescue officials have said that would be 15 minutes to an hour after the detonation.

No one has been rescued alive since the first hours after the June 24 collapse.

The search at the Surfside 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.”

So far, rescuers have recovered the remains of 24 people, with 121 still missing. Many others barely escaped. The Miami-Dade Police Department on Saturday night added Graciela Cattarossi, 48, and Gonzalo Torre, 81, to the list of those confirmed dead.

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 (64 kph).

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.

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. They did not immediately respond to an inquiry about how the firm was selected, but a contract for the projects calls for the state to pay the company $935,000.

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. The company was supposed to place explosives on the basement and lobby levels of the still-standing structure, according to the contract for the work.

CDI is “probably one of the best” in the industry, said Steve Schwartz, a member of the National Demolition Association’s board of directors. He described the company’s president and owner, Mark Loizeaux, as “cool, calm and collected.”

In implosions — using explosives to have a building fall in on itself — the charges are generally set off in rapid succession over a matter of seconds, said Scott Homrich, who heads the National Demolition Association and runs his own demolition company in Detroit, Michigan. Setting the explosives off at intervals serves to break up the building at the same time it’s coming down.

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.

Officials acknowledged that the tragedy is continuing to unfold during the July 4th holiday.

“This July 4 we’re reminded that patriotism isn’t just about loyalty to country,” said Levine Cava. “It’s about loyalty to one another — to our communities, to those in need whose names or stories we may not know ever, but to whom we are connected by compassion and by resilience.”

(AP)