Officials said that rescue efforts at the site of the collapsed Surfside, Florida condominium building were halted on Thursday out of concern about the stability of the remaining structure. Search crews that have working over the last week stopped work shortly after 2 a.m., Miami-Dade County Mayor Daniella Levine Cava told a news conference.

The halt in rescue efforts came on the same day that crews and relatives of those still missing met with President Joe Biden. The president’s visit comes a week after Champlain Towers South, a 12-story beachfront condominium building in Surfside, suddenly came crashing down. Biden and first lady Jill Biden thanked first responders and search and rescue teams, and met with the families of victims. Biden commended the strength of the families of people involved in the condo collapse, and after visiting the site with Mrs. Biden, the president said that the families were “realistic” about the prospect that the chances of their loved ones’ survival decreases by the day but said “at minimum” they hope to recover the bodies.

The number of confirmed dead is now 18, with residents still unaccounted for standing at 145. Concerns remained that the still standing portion of the complex could also collapse, with Miami-Dade Fire Rescue Assistant Chief Raide Jadallah saying: “What we know is that the columns on the east side of the building are kind of, of concern, not compromised, but just right now of concern. Hypothetically, worst-case scenario: If these columns are truly really bad, we are worried they could collapse right back into the parking garage.”