Dozens of condominiums in a Surfside, Florida, residential tower were destroyed when part of the building collapsed early Thursday.
At least one person was killed, Mayor Charles Burkett said, and 99 people were unaccounted for as of Thursday mid-afternoon, the Miami-Dade Police Department said.
A search-and-rescue operation is underway after one side of the building fell to the ground around 1:30 a.m. for reasons that remain under investigation.
Here is what we know about the building and surrounding area:
Address: 8777 Collins Avenue
Stories: 12 (the building stands about 160 feet tall)
Residences: The oceanfront building contained 136 one-, two- and three-bedroom units, according to real estate records. Most are between 1,200 and 2,243 square feet.
Price: Most condos range from $295,000 (for a one-bedroom in March 2020) to $980,000 (for a three-bedroom a year later), real estate records indicate. A four-bedroom penthouse spanning more than 4,500 square feet sold for almost $2.9 million earlier this year.
Other amenities: In addition to housing, the building offered terraces, a club room, tennis courts, fitness center, sauna, private beach, heated swimming pool, underground parking deck and 24-hour security.
Ongoing construction: At the time of the collapse, the building was undergoing work on its concrete roof, Burkett said, but it's unclear whether the work was a factor in the collapse. Work was being done to meet "40-year standards," a strengthening of the building code -- regarding updates and improvements -- enacted following Hurricane Andrew in 1992, Miami-Dade County Commissioner Sally Heyman said.
Building sunk in 1990s: Shimon Wdowinski, a professor with Florida International University's Institute of Environment, said he determined in a study last year that the building showed signs of sinking in the 1990s. The condo had a "subsidence" rate of about 2 millimeters a year from 1993 to 1999, according to his study, as first reported by USA Today.
While Wdowinski said this sinking alone would likely not cause the condo's collapse, it could be a contributing factor. "If one part of the building moves with respect to the other, that could cause some tension and cracks," he explained to CNN.
What's nearby: Champlain Towers South is one of three buildings (there are also east and north towers) that host more than 300 collective residences. It's located along the Atlantic Way in Surfside, about a block from North Beach Oceanside Park and sandwiched between Bal Harbour to the north and Miami Beach to the south.
The tower sits among several tony condominium and hotel towers, including the Four Seasons Hotel at The Surf Club, a few blocks north. Ivanka Trump and husband Jared Kushner reportedly relocated to a nearby residence earlier this year.
Who lives in Surfside: The population is 5,700. About 54% residents are non-Hispanic White, while 45% identify as Latino or Hispanic, according to the US Census Bureau. In 2018, Surfside was home to about 2,500 Orthodox Jewish residents, according to The Times of Israel, and there are at least five synagogues within a short drive of Champlain Towers.
More about Surfside: The town sits on a barrier island between the Biscayne Bay and Atlantic Ocean. The median rent is about $2,000; median household income is $69,000; and median home value is $626,000, July 2019 census records say.