Miami condo collapse: Death toll rises to 9, Surfside sister building to be probed by 'army of engineers'

The mayor of Surfside, Fla. stressed Sunday that the first priority of rescue crews is to find the some 156 building occupants who remain unaccounted for and reunite them with their families – as the cause of the 12-story building collapse remains unclear four days later and alternate housing will be provided for residents in a sister building as an "army of engineers" is set to set to begin a "top to bottom" review of its infrastructure.

"Our first priority and our only priority is to pull our residents out of that rubble and reunite them with their family who are understandably out of their minds with emotion, sadness, anger and just confused and want to know what’s happening," Surfside Mayor Charles Burkett told ABC's "This Week." "Our duty is to continue to do our jobs, which is to find their loved ones and reunited them."  What caused Champlain Towers South to collapse remains unclear, though Burkett, speaking to ABC, compared the 30-foot pile of pancaked concrete and mangled metal that rescuers continued to comb through for survivors as similar tedious rescue efforts that happened after the 2001 terrorist attack on the World Trade Center in New York City.