The emergency response from Florida Power & Light is “well underway” as Hurricane Ian approaches, the utility company announced Monday.

FP&L has mobilized 13,000 workers, as well as supplies, to ensure the response is conducted as safely and quickly as possible after the storm hits, according to a press release.

As the hurricane begins to bear down on the region, FP&L will use remote grid technology to restore power remotely during the storm, as long as it is safe to do so, the company said. After the storm passes and winds drop below 35 mph, FP&L will continue restoration and conduct damage assessments with field crews.

The utility company also urged customers to make preparations and take safety precautions.

"As this storm approaches Florida, we know our customers are counting on us and we are determined to meet this challenge," said Eric Silagy, chairman and CEO of FP&L in a statement. "We are mobilizing and pre-positioning our restoration workforce, so these brave men and women can quickly start working as soon as it is safe to do so."

-ABC News' Matt Foster

Florida State University has canceled classes Tuesday through Friday as Hurricane Ian approaches.

"The cancellation of classes on Tuesday is to allow students to travel safely out of the area if they so choose," the university said. "Students who choose to stay in Tallahassee will be advised via the FSU Alert system to follow a 'shelter in place' protocol during the storm."

The St. Pete-Clearwater International Airport will close at 1 p.m. Tuesday due to the mandatory evacuation orders in Pinellas County. The airport will stay closed until the evacuation order is lifted.

Mandatory evacuation orders are in place for coastal parts of Hillsborough County, Florida. Over 300,000 people are expected to evacuate, officials announced Monday, with emergency shelters opening at 2 p.m. Monday.

Hillsborough County could face up to 15 feet of storm surge and 30 straight hours of tropical storm force winds, Florida Emergency Management Director Tim Dudley said.

County Administrator Bonnie Wise added, “We did not make this decision easily, but the storm poses a serious threat, and we must do everything we can protect our residents.”

Some residents of Sarasota County and Manatee County are also under mandatory evacuation orders.

-ABC News’ Alex Faul

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.