Soaked South Carolina residents still knee-deep in deadly floodwaters early Monday were warned it was going to get worse before it gets better after an historic drenching.
Parts of the state were being told to expect as much as another three inches of rain before the storm which triggered flash flooding and smashed rainfall records moved offshore by the afternoon.
At least seven people have already died in weather-related incidents across North Carolina and South Carolina since Thursday, according to authorities. The victims included highway worker Timothy Wayne Gibson, whose truck swept away by "rushing flood waters" on Sunday in Columbia.
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The conditions prompted officials to warn residents not to leave their homes for any reason — even on foot.
With 20,000 homes and businesses without power across the state early Monday, the National Weather Service also warned people of winds gusting to 30 mph, increasing the risk of falling trees.
Local officials counted several hundred water rescues by mid-morning Sunday before Columbia Fire Chief Aubry Jenkins said that there were too many rescues to keep count.
Authorities in Columbia told all 375,000 of its water customers to boil water before drinking because of water line breaks and the threat of rising water to a treatment plant.
Among the rescued were 90 people — including several elderly people and dozens of pets — who were forced to evacuate their homes in Irmo, 10 miles northwest of Columbia, NBC station WIS reported.
Local fire officials said the Irmo flooding was due to the rainfall, as well as the decision to open a nearby dam in an attempt to control rising water levels.
"We didn't get the word that they were going to open the dam until 7 p.m. [Sunday] on the news," local resident Cindie Denning told WIS. "Nobody told us."
The all-time state record for the most rain in 24 hours was 14.80 inches, set during Hurricane Floyd in 1999. This was broken in several places over the weekend, with gauges registering 21.66 inches of rain falling in Dalzell, 30 miles east of Columbia, as of 9:46 p.m. Sunday, according to The Weather Channel.
Experts said parts of South Carolina experienced a "1000 year flood event," meaning in any given year there is a 1-in-1000 chance of observing such rainfall totals.
Myrtle Beach was "ground zero" for the storm Monday, with the heaviest rain expected there, although the precipitation could move through Charleston before heading out to sea, Weather Channel lead meteorologist Kevin Roth said.
"After [Monday] morning, the end is in sight," he said. "This should be the last of any kind of rain [in the region] for the next seven days."
Areas of southeast North Carolina could be hit by more downpours in the afternoon but the region would otherwise be dry, Roth added.
NBC News meteorologist Bill Karins said that "95 percent of the damage has already been done in South Carolina and waters levels in most cases are beginning to recede."
But he added: "Rivers all through South Carolina are running exceptionally high and will cause further damage into Wednesday even though it will be sunny by then."
The storm was super-charged by the effects of Hurricane Joaquin, which battered the Bahamas on Friday. It was 125 miles north of Bermuda at 5 a.m. ET on Monday.