Officials are calling off the hunt for survivors two weeks after a residential condo building collapsed in Surfside, Florida, with the death toll at 54 and 86 people still missing.

Daniella Levine Cava, Miami-Dade County mayor, said on Wednesday evening that rescue personnel had “used every possible strategy and every piece of technology available to them”, removing 7m pounds of concrete and debris during the search through the rubble in the affluent municipality north of Miami.

While “we have all asked God for a miracle”, Cava said, “at this point we have truly exhausted every option available to us in the search and rescue mission”.

Charles Burkett, Surfside mayor, added that “the possibility of someone still alive is near zero. Today is a heartbreaking day.”

The operation will switch from a rescue to an attempt to find and identify victims at midnight. Cava said the effort would continue with the “same speed and intensity”.

The 12-story building, Champlain Towers South, was constructed in the early 1980s and was seeking to obtain its 40-year recertification, which local building codes require. A 2018 report found “a major error” in how the building’s pool deck was constructed as well as “abundant” deterioration of its concrete columns and walls.

The cost of fixing the problems started at $9m but ballooned to $15m over three years while members of the condo board and residents disagreed on the price and extent of the repairs.

The problems named in the report have not been identified as the cause of the collapse, which officials are continuing to investigate.

Officials demolished the remains of the building on Sunday, because of concerns that Tropical Storm Elsa would disrupt efforts to conduct the search.

A block away survivors and well-wishers have created an impromptu memorial with flowers and photographs of the missing and candles.