President Joe Biden told reporters from the Oval Office he will travel to North Carolina on Wednesday to survey the damage.

He said he plans to land in Raleigh for a briefing and then do an aerial tour of Asheville to avoid straining on-the-ground resources.

He said he will visit Georgia and Florida "as soon as possible after that."

Asked by ABC News' Karen Travers how Americans can help out, Biden recommended people reach out to the Red Cross -- and gear up for a long recovery.

"There is a lot to do, and this is just beginning," Biden said. "We've been through this before, but not -- not like this. This is the worst ever."

-ABC News' Cheyenne Haslett

Vice President Kamala Harris called the storm damage throughout the Southeast the "worst destruction and devastation that we have seen in quite some time" during remarks from FEMA's headquarters in Washington, D.C., Monday afternoon.

"In coordination with state and local officials, President Biden and I will continue to make sure that communities have the support and the resources that they need -- not only to respond to this storm and its immediate aftermath, but also the resources they will need to recover," Harris said.

Harris said more than 3,300 federal personnel are on the ground to assist with recovery efforts, including deploying food, water and generators as well as helping to restore water and power.

"To everyone who has been impacted by this storm, and to all of those of you who are rightly feeling overwhelmed by the destruction and the loss, our nation is with you," she said. "We will continue to do everything we can to help you recover and to help you rebuild. No matter how long it takes."

Harris said she has spoken to Georgia Gov. Brian Kemp and North Carolina Gov. Roy Cooper and plans to be "on the ground as soon as possible" without disrupting any emergency response operations.

Helene is "an unprecedented storm" for western North Carolina, requiring an "unprecedented response," North Carolina Gov. Roy Cooper said Monday.

"We’re dealing with a situation that is unlike anybody’s ever seen in western North Carolina," he said.

The damage is "extensive and devastating" and is "going to require significant resources, both in the short-term and the long-term," the governor said.

Ninety-two rescue teams are out conducting search and rescues right now, Cooper said.

More than 300 roads are closed and some bridges have been destroyed, officials said.

Over 7,000 North Carolina residents have registered for FEMA individual assistance and that money is already flowing in, according to Will Ray, director of North Carolina Emergency Management.

FEMA Administrator Deanne Criswell promised that the agency will "be here as long as it takes to finish this response and continue through the recovery."

"We have the resources here in North Carolina to help," Criswell said. "We will continue to send additional resources in."

Homeland security adviser Liz Sherwood Randall said the full extent of the damage from the hurricane is still unclear.

“It probably will take several more days, as communities begin to be opened up by the debris clearance on the roads, and we can get in, and really understand what's happened to them," she said.

Sherwood-Randall said about 600 people are unaccounted for.

“We're very hopeful that some of those people just don't have cellphones working and actually are alive," she said.

Sherwood-Randall said 3,500 federal response personnel have been deployed to the region and additional personnel is expected to arrive in the coming days.

With communication remaining a major challenge, Sherwood-Randall said, "Today, FEMA will install 30 Starlink receivers in western North Carolina to provide immediate connectivity for those in greatest need."

She also highlighted that in states that have received major disaster declarations, FEMA is working to distribute serious needs assistance, which gives "an immediate $750 direct payment to eligible households, to allow them to pay for essential items like food, baby formula, water, medications and other emergency supplies."

-ABC News’ Molly Nagle

The remnants of Hurricane Helene were not the only factor that contributed to the severity of the flooding that struck the mountain community of Asheville, North Carolina.

Several conditions in the region, including a precursor rain event and the topography of the land, gave rise to deadly flash flooding, experts told ABC News.

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