More than 1.6 million electricity customers in Florida remained without power Friday, two days after Hurricane Ian caused severe destruction in parts of the state, and utilities said some outages will be prolonged.

The number, released by the Florida Division of Emergency Management around 6 p.m., is down from the more than 2 million after Ian struck Wednesday.

In southwest Florida, customers will face “prolonged outages," Florida Light & Power said. There was no immediate estimate for restoration in Lee, Charlotte, and some other hard-hit counties.

Kevin Guthrie, director of the state emergency management division, on Friday warned residents about the danger of carbon monoxide poisoning. posed by improper use of generators.

“We still get reports of people operating their generators inside of a garage, operating their generators just outside of a cracked window with the cord running through the window,” he said at a news conference.

Carbon monoxide from generators has killed people following other hurricanes. After Hurricane Laura hit Louisiana in 2020, nine of the 31 deaths there were people who died of carbon monoxide poisoning, health officials have said. All but four died of “indirect” causes like heat illness and during cleanup, according to the National Hurricane Center.

Crews are beginning to repair — and in some cases, rebuild — Florida’s power grid after the state was pummeled by Hurricane Ian.

Florida Power & Light says it stockpiled enough poles, generators and wire to do the work. But power-industry officials warn that kinks in the nation’s supply chain could slow the recovery if Ian causes more damage as it spins up the Atlantic coast, or when another natural disaster strikes somewhere else in the U.S.

Eric Silagy, CEO of Florida Power & Light, said that Friday evening 850,000 of the utility’s customers who lost power in the storm remained without power, but 1.2 million had power restored during the day.

Silagy said earlier this week that the company had set aside enough generators in the months before Ian to complete repairs.

Nationally, however, there is a shortage of distribution transformers that take electricity from high-voltage lines and reduce it to levels that can be used in homes and businesses, industry officials said.

“It’s a critical component to the electrical grid that has been in scarce supply for a number of months now,” said Joy Ditto, president and CEO of the American Public Power Association. “We started to recognize it as a national concern in late winter, early spring, and the situation is getting worse.”

It used to take about three months for a transformer to show up after being ordered, but now it is taking more than a year, Ditto said. She said that is limiting the ability of companies to stockpile the boxes, and as a result, they are increasingly swapping boxes with utilities facing a shortage.

Twenty-one people have died after Hurricane Ian slammed into Florida earlier this week, according to an NBC News tally.

At least seven of those deaths appear to have been drownings, the Florida Medical Examiners Commission said in a Friday update.

Speaking to reporters earlier in the day, Florida Gov. Ron DeSantis confirmed there have been casualties in the wake of Ian but would not comment on how many, adding that some people might experience medical emergencies that are not directly related to the hurricane.

"Some times there are deaths that are not attributable to the storm" he said, citing an example from Charlotte County where someone suffered a heart attack but could not receive timely medical attention.

Hurricane Ian walloped South Carolina with storm surge flooding, but the state's governor said at a news conference Friday afternoon that Ian — now a post-tropical cyclone — was "not as bad as it could have been."

Still, he warned, residents there need to remain vigilant.

"Don't quit yet, because this is still coming," Gov. Henry McMaster said. "We're not out of the woods."

The National Hurricane Center has downgraded Hurricane Ian to a post-tropical cyclone after it made landfall in the Carolinas.

Warnings for high wind threat, dangerous storm surge and flash flooding continue, and a tropical storm warning has been issued from Edisto Beach in South Carolina to Cape Fear in North Carolina, the NHC said in an advisory.

"The combination of storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline," the advisory warned.

Ian is forecast to move farther inland overnight to eastern South Carolina, move across central North Carolina early Saturday and reach western Virginia by early Sunday.

Power outages are steadily ticking upwards in South Carolina, where some 212,802 customers are in the dark as of 4:20 p.m. ET, according to PowerOutage.us.

"Crews will be working around the clock to get the lights back on as quickly and safely as possible," Dominion Energy, the utility experiencing the most outages in the state, said in a tweet.