A Coast Guard boat patrols in front of the partially collapsed Champlain Towers South condo building, ahead of a planned visit to the site by President Joe Biden, on Thursday, July 1, 2021, in Surfside, Fla. Rescue efforts at the site of the partially collapsed condominium building were halted Thursday out of concern about the stability of the remaining structure, officials said.

SURFSIDE, Fla. — Rescue efforts at the site of a partially collapsed Florida condominium building resumed Thursday evening, about 15 hours after the work was halted out of concern about the stability of the remaining structure, the mayor said.

Surfside Mayor Charles Burkett said he did not know why officials decided to restart the search. Rescuers left the pile of rubble shortly after 2 a.m. after crews noticed widening cracks and up to a foot of movement in a large column.

“Finding missing loved ones continues to be at the forefront of our operations,” Miami-Dade Fire Rescue tweeted soon after search efforts resumed.

The stoppage threatened to keep search teams off the rubble pile and dim hopes for finding anyone alive in the debris a week after the tower came down.

The rescue operations unfolded on the same day that President Joe Biden and first lady Jill Biden visited the devastated community.

The collapse of the 12-story Champlain Towers South beachfront condominium killed at least 18 people and left 145 missing. Hundreds of search-and-rescue personnel have painstakingly searched the pancaked rubble for potential signs of life, but no one has been rescued since the first hours after the collapse.

“This is life and death,” Biden said during a briefing. “We can do it, just the simple act of everyone doing what needs to be done, makes a difference.”

Heavy equipment in the rubble pile caused vibrations, according to Nacheman. Rain has also been entering exposed parts of the building, saturating items and adding weight to the floors.