Loading Video…

This browser does not support the Video element.

TAMPA, Fla. - Hurricane Milton left more than 3 million Florida residents without power when it tore across the state, and officials are pleading for patience as crews work around the clock to get the lights back on.

Hillsborough County was one of the heaviest-hit areas. The head of local electric company Tampa Electric (TECO) explained during a press conference Thursday afternoon that nearly 600,000 of TECO's 850,000 customers were without power, and laid out the challenges workers face in restoring it.

TECO President Archie Collins said that to his knowledge, this is the largest outage the company has ever had.

Florida power outages: Hurricane Milton knocks out power to millions

Milton was expected to cause devastation, and Collins said TECO prepared ahead of time. He said 6,000 utility workers have been assembled to assist with restoring services, and noted that the most he has seen involved in previous hurricanes in his seven years at the company was 3,500.

Still, they have their work cut out for them.

Much of Thursday was spent assessing the extent of the damage. Helicopters were sent out to fly up and down the transmission grid to find sources of outages. The area has extensive localized flooding from heavy rains, which, coupled with strong winds, has caused some overhead infrastructure to sway, Collins said.

Hillsborough County Deputy Sheriff Colonel Anthony Collins said first responders, including police and firefighters, are working as hard as they can, and reported multiple downed trees, which was delaying some rescue efforts.

"We can't get to them as soon as possible because…a lot of those trees are coming with electrical wire," Collins said. "We don't know if those wires are live or if they're inactive, so just please be patient with us." He added that many traffic control devices are inoperable, too.

Tampa Mayor Jane Castor said that because of the "massive" outages, 65% of the traffic lights are out in the city of Tampa, and that she could only imagine the percentage that are out of power countywide.

READ: Possible sinkhole nearly swallows two Polk County homes after Hurricane Milton

"We have a lot of work to do, but we need you to do your part as well," Castor said. She joked that everybody behind her at the press conference might think she smelled "like an arsonist" because he had just gassed up and started a generator for one of her sisters.

"We're going to get the electricity back on, but you also have to be cognizant of those down lines and make sure, again, that you are helping take care of your neighbors," she added.

Andy Ross, the mayor of Temple Terrace, used his time at the press conference to urge residents to "stay the course," emphasizing that officials realize the inconvenience of not having electricity and are doing all they can to get it restored – but it could take some time. He warned residents, "This is not going to happen by Saturday."

Video: Boat captain found clinging to cooler 30 miles off Longboat Key after surviving Hurricane Milton at sea

TECO's Collins said he expects some "lucky" customers would see power back on as early as Thursday from crews working on restoration on a circuit-by-circuit basis. But restoration is made in tiers, with first priority going to places like hospitals and nursing homes, then critical infrastructure like the airport, and then, finally, the residential community.

"We completely understand that the continuity of electric supply is foundational to just a functioning society and a burgeoning economy, and we are committed. We have the resources," Collins said. "We're going to need a little bit of patience from our customers and from our community partners, but we will get this system restored in short order. It's just – we just need a little bit of time today to sort of work through the triaging."