Matthew’s wrath is finally over, but its devastation keeps growing and rescue crews stayed busy.

The storm’s US death toll climbed to 21 on Monday, with North Carolina reporting 11 deaths, Florida reporting four, and three each in South Carolina and Georgia.

Carolina rescues

In the eastern North Carolina city of Lumberton, rescuers on Monday were scrambling to save 1,500 people stranded by flooding.

“We have people on roofs (there) as we speak,” North Carolina Gov. Pat McCrory said. The Federal Aviation Administration has ordered flight restrictions over the area so helicopters can rescue them.

CNN affiliate WRAL said state officials initially said the flooding occurred because of a break in a levee along the Lumber River.

But it later reported that the National Oceanic and Atmospheric Administration said the levee was intact.

The station cites NOAA’s Richard Neuherz as saying that “water was flowing into the southwest portion of the city” via an interstate underpass. “The flooding would have happened more quickly and with more devastating effects if the levee had failed,” the report said.

Authorities in Marion County used boats and helicopters to rescue the last members of a group of 150 people who sought shelter against the Lumber River in the Nichols, South Carolina, town hall.

People had been in the town hall since 9 p.m. Sunday, according to Kent Williams, who is the Marion County deputy administrator and a state legislator.

“With the Lumber River and all the rain that Matthew dumped on us, it was more than they could handle. That was pretty much the safest place for them to be,” Williams said. “The town hall was the high ground.”

Rescue teams took them to a middle school in Mullins.

“The water is rising so fast it’s scary. The river is not scheduled to crest until ten in the morning. It’s the worst we’ve seen it,” Williams said.

Massive power outages

About 500,000 structures in North Carolina didn’t have power Monday.

“That’s probably well over 1 million people without power,” McCrory said. “That’s 10% of our population in North Carolina — all in a very small area. At least 10%.”

Matthew’s damage exceeded expectations, Duke Energy said. The power company said it now has to rebuild parts of the electrical system. It said some of the hardest-hit areas “might be without power all week.”

More than 469,000 South Carolina customers didn’t have power Monday, Gov. Nikki Haley said. She said 8,000 linemen were working to get electricity restored.

And Florida, the first state thrashed by Matthew, still had 169,000 customers without power Monday, Gov. Rick Scott’s office said.

Dead and missing

The 11 deaths in North Carolina included some victims who drowned after driving onto flooded roads.

“I cannot stress more: If you see a road that’s flooded, do not take your car through that road,” McCrory said. “If you see a barrier, do not go around that barrier.”

Another five people remain missing in North Carolina, McCrory said.

In South Carolina, 66-year-old David L. Outlaw drowned when his wheelchair got pinned down in standing water at a nursing facility’s courtyard, Richland County Coroner Gary Watts said.

The US deaths came after Matthew devastated parts of the Caribbean, killing more than 300 people in Haiti, said Paul Altidor, Haitian ambassador to the United States. Others report much higher death tolls.

More ‘catastrophic flooding’ on the way

Forecasters warned of more “catastrophic flooding” as North Carolina residents braced for swollen rivers to top their banks in the next few days.

“River levels will rise above major flood stage this morning and remain elevated well into next week,” the National Weather Service said.

What to do next

As more storm victims return to their homes from Florida to North Carolina, it’s critical to know how to come back safely.

In addition to avoiding all flooded roads, keep an eye out for downed power lines and weakened bridges and roads that look like they might collapse, the National Weather Service said.

Once back home, “walk carefully around the outside of your home to check for loose power lines, gas leaks and structural damage,” the NWS said. “Stay out of any building if you smell gas.”

The agency said carbon monoxide poisoning is one of the leading causes of death after storms involving power outages.

“Never use a portable generator inside your home or garage,” the NWS said. “Use battery-powered flashlights. Do not use candles. Turn on your flashlight before entering a vacated building. The battery could produce a spark that could ignite leaking gas, if present.”

North Carolina’s Department of Public Safety offers additional tips on how to safely remove trees and limbs from homes.

Beach house turns into a beach

Grant Lynch garnered national attention last week when he posted video of Matthew’s mammoth waves clobbering his Florida beach house.

He returned to his Palm Coast home over the weekend to find the house filled with beach sand.

“The whole yard is now a beach,” Lynch said.

He tried to walk inside the house, whose floors were covered by what looked like more than a foot of sand.

“My head’s almost hitting the roof,” he said.