Hurricane Milton updates: 16 dead across Florida in storm's aftermath

In Pinellas County, which encompasses Clearwater and St. Petersburg on Florida's west coast, residents "are running out of time" to evacuate, county communications director Barbra Hernandez said Wednesday.

"Our goal is to reduce the loss of life. Please get yourself out of harm’s way now," she said. "We don’t want to be plucking people out of the water."

"This will be a knockout," county emergency management director Cathie Perkins added. "Buildings, homes, wiped off foundations. That is unsurvivable."

Mandatory evacuations have been issued in parts of the county. By dusk on Wednesday, all bridges off the peninsula will be closed and first responders will be pulled off the roads due to flooding and high winds, Perkins said.

"You’ll be on your own after that," she warned.

-ABC News’ Jason Volack

Milton could be "like nothing they have seen before," FEMA Administrator Deanne Criswell warned on ABC News' "Good Morning America."

"While you can ride out a storm and hide from the wind, you need to move away from the water," she said.

"The water is what kills people," Criswell said. "Nobody has to die from this storm. They just need to move out of the evacuation zone area into a place that is going to be safe from the storm surge."

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Mandatory evacuation orders have been issued in parts of over a dozen Florida counties: Charlotte, Citrus, Collier, Flagler, Hernando, Hillsborough, Lee, Levy, Manatee, Marion, Pasco, Pinellas, Sarasota, St. Johns and Volusia.

"If you live in a storm surge evacuation zone and you're asked to leave by your local officials, please do that," Michael Brennan, the director of NOAA's National Hurricane Center, told ABC News Live on Sunday. "You don't have to drive hundreds of miles to get to a safe place, often just tens of miles to get inland, out of that evacuation zone, to a shelter, a friend or loved one's home."

Brennan also urged Floridians to prepare a disaster kit with several days’ worth of nonperishable food, water, medicine and batteries.

President Joe Biden spoke to local officials from Clearwater and Pinellas County, Florida, Tuesday night to talk about the "ongoing preparations for Hurricane Milton," the White House said.

The president told Clearwater Mayor Bruce Rector and Pinellas County Chairwoman Kathleen Peters "to call him directly if they need additional assistance on response and recovery efforts," the White House added.

-ABC News' Michelle Stoddart