Idalia updates: Damaging tornadoes, severe flooding from Florida to Carolinas

FEMA Administrator Deanne Criswell said she's flying to Florida on Wednesday and will meet with Gov. Ron DeSantis on Thursday.

She said her "biggest concern is those people who chose not to evacuate."

"We're already getting reports of people that chose to stay, and they're getting calls on into the local first responders to come in and assist them," she said.

As the storm moves north into Georgia, Criswell warned Floridians to still be mindful of flooded roads.

"As you do go out, do not wade in the water," she added. "Do not drive through flooded roads and streets. Just remember, turn around, don't drown. Unfortunately, we see so many fatalities after the storm passes. We want to make sure that everybody is taking the right precautions."

She said it will "take several days to get a full understanding of what the initial assessment, damage assessment is," and "will take longer to get the full picture of the total amount of impact to these communities."

-ABC News' Ben Gittleson

Despite reports of fatalities from Hurricane Idalia -- including at least one death in Pasco County confirmed by the Florida Highway Patrol -- Florida Gov. Ron DeSantis said Wednesday that none of the reported deaths have yet been confirmed.

"There’s a process for confirmed fatalities that just goes through law enforcement and medical examiners. … That has not been done yet where we've had a confirmation," he said.

Health facilities largely avoided damage and evacuations, Florida Division of Emergency Management Kevin Guthrie said.

"As of this minute, there have been no reports of any issues inside the health and medical industry, whether that’s assisted living facilities, skilled nursing facilities, nursing homes or hospitals," he said.

The city of Perry, Florida, suffered some of the heaviest damage, officials said. Multiple businesses were on fire and several buildings lost their roofs.

Over 270,000 customers in Florida lost power due to Idalia. The governor said crews are working quickly to restore power to those still in the dark.

-ABC News' Will McDuffie and Hannah Demissie

A 100-year-old oak tree split open and toppled onto the governor's mansion in Tallahassee, Florida, on Wednesday, according to a tweet from Casey DeSantis, wife of Gov. Ron DeSantis.

Casey DeSantis said she and their children were home at the time but were not hurt.

In Pasco County, Florida, just north of Tampa, authorities helped evacuate more than 60 people from flooded homes, according to the sheriff's office.

The county is facing flooded roads, downed trees and downed power lines in the aftermath of Idalia, the sheriff's office said.