Lee County Sheriff Carmine Marceno told ABC News' "Good Morning America" that Hurricane Ian was very unpredictable, with officials tracking the storm every minute and they didn't know where it would hit.

"This is a life-changing event for all of us. We tracked that storm up the coast of Florida, it was very unpredictable," Marceno said.

He added, "We didn't know where it would hit. I can tell you it came into Lee County strong and it was slow moving."

Marceno said there were fatalities, but he didn't yet know the exact number.

Marceno said they are already assessing the area, but the whole area is "crushed" and people are trapped. Marceno said they have thousands of 911 calls that they are currently answering.

"We still cannot access many of the people that are in need," Marceno said. "It's a real, real rough road ahead."

In Volusia County, on Florida's east coast, authorities said one person has been confirmed dead. A 72-year-old man who went outside to drain his pool was swept away and found dead in a canal behind the house.

President Joe Biden has approved a major disaster declaration for Florida residents in Charlotte, Collier, DeSoto, Hardee, Hillsborough, Lee, Manatee, Pinellas and Sarasota counties.

"Assistance can include grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses, and other programs to help individuals and business owners recover from the effects of the disaster," the White House said.

-ABC News' Justin Gomez

Flooding has hit several parts of the Orlando area, including Seminole, Osceola, Lake counties and other neighboring areas.

ABC News' Orlando affiliate WFTV said that first responders in Kissimmee rescued at least one person from a couple of vehicles that had been partially submerged during a storm surge overnight.

It is unclear how severe the damage is in the area but witnesses reported heavy and sustained wind and rain throughout the overnight hours.

-ABC News' Ahmad Hemingway

A flash flood emergency was declared in areas north of Orlando as the region was hit by about a foot of rain, the National Weather Service said.

The declaration covered Sanford, Lake Mary and Heathrow, the service said. Nearby Central Orange, Seminole and South Central Volusia were also under flash flood warnings.

“This is a particularly dangerous situation,” the service said. “Seek higher ground now! Life threatening flash flooding of low water crossings, small creeks and streams, urban areas, highways, streets and underpasses.”

Parts of the region have seen more than 16 inches of rain within 24 hours, with more than 9 inches in the last six hours, making the storm a 1,000-year flood event in the Orlando area and to the north.

-ABC News’ Max Golembo and Kenton Gewecke