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At least four are dead and 159 others still missing after a condominium tower in Surfside, Florida partially collapsed Thursday morning, CNN reports. And although the cause of the disaster is still unknown, some Champlain Towers residents reportedly complained of issues of "structural integrity and serious disrepair" prior to the building's tragic collapse, per The New York Times.

In 2015, one Champlain Towers resident sued the condo association, claiming poor building maintenance had "allowed water to damage her unit after entering cracks through the outside wall," the Times writes. Other residents reported feeling "ground reverberations" during the demolition and construction of a new building nearby. A 2020 study also found the building had been sinking into the Earth "at an alarming rate" since the 1990s, USA Today reports.

"About a month ago I was standing on the balcony and saying, 'This is not safe,'" said Adriana Gonzalez Chi, sister of missing Champlain Towers resident Edgar Gonzalez. She said she warned her brother "numerous times" that the complex felt unsound, due in part to "frequent complaints about leaks and mold," writes the Times.

Gonzalez Chi said she told her niece, "If you feel the building tremble, run."

The building was preparing to undergo "extensive repairs for rusted steel and damaged concrete," said Kenneth S. Direktor, a lawyer for the resident-led association that operates the Champlain Towers South building. However, he claimed he'd seen "nothing to suggest" those issues had contributed to the collapse.

Read more at The New York Times.