Lee Health, the Florida-based health care system, has evacuated patients out of three of its four hospitals because they don't have running water due to Hurricane Ian, Dr. Larry Antonucci, president and CEO, said in a video statement Thursday.

“At the present time, our structures and facilities are in good shape. They’ve weathered the storm well, but our infrastructure is challenged in the way of our water supply and power,” Antonucci said.

Lee Health is working with the Agency for Health Care Administration in Florida and local emergency management to arrange for the evacuations of patients to other hospitals outside of Lee County, which includes Fort Myers.

-ABC News' Alexandra Faul

Disney World, which was shut down Wednesday and Thursday, will begin a phased reopening on Friday, according to the resort.

The theme parks and Disney Springs will begin reopening "as we assess the impact of Hurricane Ian on our property," Disney tweeted.

The exact opening hours will be released later Thursday, Disney said.

More than a foot of rain has already fallen in the Orlando area with some light rain still ongoing. Hundreds of people have been rescued from flooding in the city.

Ian is expected to be at least a Category 1 hurricane with 75 mph winds when it makes its third landfall near or north of Charleston, South Carolina, Friday, in the late morning or early afternoon.

Ian, currently a high-end tropical storm with winds up to 70 mph, is moving off the east-central coast of Florida, currently 40 miles northeast of Cape Canaveral. The storm is forecast to regain hurricane strength in the next 12 hours.

Hurricane warnings remain in effect for the entire coast of South Carolina. Charleston already had almost 2 foot storm surge Thursday as Ian gets closer, and storm surge is forecast up to 7 feet.

The storm surge combined with up to 10 to 12 inches of rain is extremely concerning as the area floods easily.

-ABC News' Melissa Griffin

President Joe Biden said officials are hearing early reports of what may be a substantial loss of life due to Hurricane Ian, he said at a press conference at Federal Emergency Management Agency headquarters Thursday.

"This could be the deadliest storm in Florida history. The numbers we have are still unclear, but we're hearing early reports of what may be substantial loss of life," Biden said.

Biden also promised support to state and local officials as officials assess the damage caused by the storm, saying the federal government will cover the entire cost of clearing debris and of rebuilding public buildings like schools and state fire stations. The government will also be providing support to people with destroyed or damaged homes.

The Federal Emergency Management Agency's search and rescue teams have been out in the field since 4 a.m. Thursday, FEMA Administrator Deanne Criswell told "Good Morning America." It will prioritize saving lives and helping people impacted by the storm, who may be trapped.

Criswell said FEMA has been hearing reports of people calling 911 through the night and will use information it has gathered in those hours to prioritize rescues in harder-hit areas.

"This has been just a catastrophic storm and it's left significant damage in its path," Criswell said.

Criswell said FEMA will be able to conduct rescues by land, air and sea.

The most significant impacts have been happening in Lee County, where people are without power and water. Criswell also expects impacts across the western coast of Florida.

"Water is dangerous. Even though the storm has passed, the water that is there is still dangerous. There's debris, there's chemicals, there could be downed power lines. People need to be careful, they need to stay vigilant," Criswell said.