The confirmed death toll in the partial collapse of a 12-story residential building in Surfside, southeastern US state Florida, has risen to 36, Miami-Dade Mayor Daniella Levine Cava said at an evening news briefing on Tuesday.

There are 109 "reports of people who are potentially unaccounted for," the mayor said.

Miami-Dade County Fire Chief Alan Cominsky said they failed to find any positive signs in regard to voids or livable spaces as rescue workers continue to search the rubble left behind.

"Unfortunately we're not seeing anything positive," Cominsky said.

Search and rescue were forced to pause for about two hours Tuesday afternoon because of lightning and some gusts of wind that went above 30 miles (48 km) per hour with Tropical Storm Elsa approaching, according to a CNN report.

The collapse occurred on June 24 at the Champlain Towers South condominium in the beachside town that sits around 9.6 km north of Miami Beach.

Since the collapse, multiple Miami-area buildings have been evacuated, local media reported.