Hurricane Helene live updates: Helene death toll reaches 200

Hundreds of thousands of customers in the South are still without power nearly one week after Hurricane Helene made landfall.

More than 380,000 customers are in the dark in South Carolina and nearly 300,000 are without power in North Carolina.

Another 268,000 are without power in Georgia.

"This has been a historic storm. We've never seen anything like this," Duke Energy spokesperson Bill Norton said. “The biggest challenge has been the unprecedented flooding. It’s not just poles and wires that are down -- it's the backbone of our system, the transmission infrastructure and substations."

"We’re still targeting end of day Friday for the majority of our customers who are able to receive power," he added.

The Tennessee Occupational Safety and Health Administration has opened an investigation following reports that flash flooding from Helene swept away employees from Impact Plastics in Erwin, Tennessee, which is located in Unicoi County.

TOSHA and the Tennessee Bureau of Investigation are working to determine what led to the "workplace fatalities" at the Erwin facility, the Tennessee Department of Labor and Workforce said in a statement.

In their evening flash update, TEMA has confirmed that four people have died due to weather-related injuries, and six people remain missing in Unicoi County. Authorities have not confirmed how many fatalities and missing people are associated with Impact Plastics.

-ABC News' Victoria Arancio

The confirmed death toll for Hurricane Helene rose to at least 189 people as of Wednesday evening, The Associated Press reported, making it the deadliest hurricane since Katrina to hit the mainland U.S.

As recovery efforts continued across the Southeast, President Joe Biden and Vice President Kamala Harris traveled to the region Wednesday to survey the destruction while rescuers keep searching for the missing.

"I'm here to say the United States -- the nation -- has your back," Biden told a crowd in Raleigh, North Carolina. "We're not leaving till you're back on your feet completely."

Ahead of a Wednesday briefing in Augusta, Georgia, Vice President Kamala Harris thanked officials for their work in the post-Hurricane Helene response and recovery efforts.

In her remarks, Harris thanked “all of the folks who are here on the ground doing this extraordinary work.”

"I've been reading and hearing about the work you've been doing over the last few days, and I think it really does represent some of the best of what we each know can be done, especially when we coordinate around local, state and federal resources, to meet the needs of people who must be seen, must be heard," she said.

"These are very difficult times, and in a moment of crisis, I think that really does bring out the best of who we are. And you, each, epitomize that important and good work," Harris added. "So, I'm here to thank you and to listen."

Click here for more details on Biden and Harris' trips to the South.

-ABC News’ Fritz Farrow, Gabriella Abdul-Hakim and Will McDuffie