For days, residents had been told to heed the warnings. Hurricane Florence , at its peak a Category 4, would be the "storm of a lifetime for portions of the Carolina coast," the National Weather Service said. It would bring powerful wind, relentless rain and life-threatening storm surge to an area that wasn't used to hurricanes.

More than 1 million people were under mandatory evacuation orders as the storm crawled toward the East Coast.

It would soon become clear why residents had been told to leave.

The calm before the storm

As Florence twisted over the Atlantic Ocean Thursday morning, 65-year-old Deb Frese took a walk along the shoreline. The Myrtle Beach, South Carolina, resident knew the storm could be keeping her inside for a while, so she wanted to fit in one last stroll.

Waves crash around Oceanana Pier in Atlantic Beach, North Carolina, as the outer bands of Hurricane Florence begin to affect the coast on Thursday, September 13.

Frese lived in the evacuation zone, about a mile from the beach, but she chose to ride the storm out in her home.

"Flooding, that's the biggest concern," said Frese. She also recognized that she might have to make do without power. But with a stockpile of food, batteries and lanterns, she was prepared to hunker down for "at least a week," she said.

"Then I might have to go."

'This is just the beginning'

By Thursday afternoon, Florence's wind speeds had dropped, and the storm was classified as a Category 2. But forecasters said its biggest threats remained: potentially deadly storm surge, flooding, and what was expected to be a historic rain event.

In New Bern, North Carolina, along the banks of the Neuse River, a CNN crew watched the water rise and flood Union Point Park until they were forced to leave.

Todd Willis, a resident of Kennel Beach, North Carolina, shared video on Facebook of tidal flooding. It was early in the afternoon, and water was already collecting beneath homes lofted on stilts. Some water inched up to the road as Willis drove by.

"This is just the beginning," he said. "It hasn't even gotten here yet and there's already water (in the) bottom parts of people's houses."

By evening, the storm was downgraded to a Category 1. But conditions continued to deteriorate into the night, as thousands of evacuees slept in emergency shelters.

Annazette Riley-Cromartie's home in eastern North Carolina began to flood around midnight. As her kids tried to sleep in a top bunk, her husband could hear voices in the distance.

"While we were still waiting, my husband kept hearing people yelling for help," she told CNN's Anderson Cooper , her voice thick with emotion. Her 6-foot-2 husband tried to go out and help, she said, but the water was already above his chest.

JUST WATCHED Florence survivor: We could hear people yelling Replay More Videos ... MUST WATCH Florence survivor: We could hear people yelling 02:15

"You just keep hearing people yelling, and you can't do anything," she said. "It's the worst feeling in the world."

"WE ARE COMING TO GET YOU," the city tweeted . "You may need to move up to the second story, or to your attic, but WE ARE COMING TO GET YOU."

By sunrise Friday, the town had seen about 7 inches of rainfall and 10 feet of storm surge, and scores of people still needed saving.

Trapped by floodwater

At 7:15 a.m., Wrightsville Beach, North Carolina, became eerily calm as the eye of Hurricane Florence, now a Category 1 storm, loomed overhead.

You just keep hearing people yelling, and you can't do anything. It's the worst feeling in the world. Annazette Riley-Cromartie

Florence, with maximum sustained winds of 90 mph, had made landfall.

Trees swayed from the wind and toppled over, blocking roads. Deserted streets flooded and swollen rivers escaped their banks. Power transformers exploded in bursts of light like fireworks, leaving hundreds of thousands of electric customers in the dark. Whole neighborhoods soon became swamps.

Back in New Bern, the Cajun Navy and other ragtag teams of volunteers joined emergency responders to rescue people from the rising water. As water poured into their homes, residents sought refuge in attics.

Neighborhoods are flooded after the storm surge from Hurricane Florence flooded the Neuse River September 14, 2018 in New Bern, North Carolina.

"In a matter of seconds, my house was flooded up to the waist, and now it is to the chest," Peggy Perry told CNN's Chris Cuomo Friday morning.

"We have been up here for like three or four hours."

In River Bend, south of New Bern, a man shouted out of his open window at a small boat that had been left behind and commandeered by the Maryland Swift Water Rescue Team.

But when they asked if he needed help, the man said no.

He had everything he needed, he said. He just wanted to say hello.

Members of the FEMA Urban Search and Rescue Task Force 4 from Oakland, California, search a flooded neighborhood for evacuees during Hurricane Florence on September 14, 2018 in Fairfield Harbour, North Carolina.

The first deaths

A tree came crashing down on a house in Wilmington, North Carolina.

A family of three was inside the home, and emergency responders worked for hours to save them.

In the afternoon, authorities confirmed that a woman and her infant daughter were dead -- the first known deaths attributed to Florence. The child's father was taken to a local hospital.

A group of firefighters who had rushed to the scene were shaken. They knelt outside the home in a circle and began to pray.

JUST WATCHED Firefighters pray for fallen Florence victims Replay More Videos ... MUST WATCH Firefighters pray for fallen Florence victims 01:01

'It's time to go'

By Friday evening, Florence had been downgraded to a Tropical Storm. But the rain showed no signs of abating and rivers continued to spill over their banks.

On Saturday morning, the National Weather Service warned of the possibility of "catastrophic flooding."

"We face walls of water at our coast, along our rivers, across farmland, in our cities and in our towns," North Carolina Gov. Roy Cooper told reporters that morning. "More people now are facing imminent threat than when the storm was just off shore."

Susan Bostic and her family had initially planned to wait out the storm in their Rocky Point, North Carolina home, not far from the Cape Fear River. They changed their minds on Saturday, as water from the river spilled onto their property, collecting in big pools on the ground.

Bostic had lived through Hurricane Floyd in 1999, she said, and it took everything -- cars, clothes, her home.

"And they're expecting this to be even higher," she said. "So we know it's time to go."

JUST WATCHED Family braces for flooding after Florence Replay More Videos ... MUST WATCH Family braces for flooding after Florence 00:58

About 40 miles to the northeast, in Jacksonville, North Carolina, Marti Dias was grappling with the same realization. She watched water from the New River slowly creep up her street, mailboxes jutting above the surface. Some of her neighbors had already left. It was time to go.

"I'm not going to lie, I cried this morning," she told CNN. "I broke down and cried."

Residents of Lumberton, North Carolina, also kept a wary eye on their own Lumber River, which quickly rose foot after foot as heavy rains continued to drench the state. The river had inundated Lumberton two years before, during Hurricane Matthew, and city officials scrambled this week to plug a hole in the town's levee system.

The statue of a horse stands in rising water at the Exchange Nature Park along the Neuse River September 15, 2018 in Kinston, North Carolina.

As floodwaters rose, roads quickly became impassable. An abandoned car was left running idle in the street with water lapping at the passenger windows.

That night, emergency responders and volunteers in Wilmington, North Carolina, made about 700 rescues; Pender County conducted 172, and lost two ambulances in the floodwaters.

By the end of the day, 13 people would be confirmed dead, several of them from flash flooding.

On Saturday evening, Hailey Burgalow was traveling to Virginia with her sister, her sister's boyfriend and her aunt when they hit flooding on Interstate 95, forcing them to pull off and venture into Lumberton.

I'm not going to lie, I cried this morning. I broke down and cried. Marti Dias

The town was still in the process of recovering from Hurricane Matthew, and many homes appeared to be abandoned or in disrepair, their windows boarded up and weeds growing tall in the yards.

The group parked at a gas station and tried to get some sleep in the car, Burgalow told CNN. Eventually, a police officer stopped, and they asked him if there was any way to make their way north. There wasn't, the officer told them. He directed them to a shelter that was filled with evacuees.

"They ran out of cots and blankets," Burgalow told CNN. "It was super crowded, but we were thankful."

On Sunday morning, Burgalow and her family realized they were stuck there.

Flooded roads and fragile levees

The National Hurricane Center issued its final advisory for Florence on Sunday morning as the storm, crawling inland, weakened to a tropical depression with maximum sustained winds of 35 mph -- but plenty of rain was still on its way.

The center said in its last advisory that southeast North Carolina could see up to 40 inches of rain, and also warned of the risks of landslides across western North Carolina and southwest Virginia.

Wilmington Mayor Bill Saffo called the flooding in the northern part of the county a "phenomenon," and "something we've never seen before." The city was essentially cut off from the rest of the state because of high waters, he said.

A member of the US Coast Guard walks down Mill Creek Road checking houses after tropical storm Florence hit Newport, North Carolina, Saturday, September 15.

"Any direction you try coming into the city -- from 20 to 40 miles out, roads are impassable," he said. "Anyone trying to get in here -- don't try. You will be turned away."

The Lumber River was close to 25 feet high by midday -- 12 feet above flood stage. At 26 feet, Lumberton city officials said, the levee around the river could be overwhelmed.

At that point, "all bets are off," said Corey Walters, deputy director of Public Works.

The rain had slowed down overnight, he said, giving officials another chance to try and plug the gap in the levee system -- but Walters didn't sound optimistic.

Robert Simmons Jr. and his kitten Survivor are rescued from floodwaters after Hurricane Florence dumped several inches of rain in the area overnight, Friday, September 14 in New Bern.

"Our crews are taking one more crack at trying to stop it," Walters said. "We're just fighting time here. There's another rain band that's going to be coming through and we know it. We're expecting to get another 4 to 6 inches."

Water began seeping beneath the sand barriers workers had placed there Sunday afternoon.

Bobby Hunt was just about finished packing belongings into the back of his pickup truck.

"Y'all ready? Let's get in the truck and get out of here," Hunt told his wife and cousin as they prepared to leave their boarded-up Lumberton home, which still bore the damage from Hurricane Matthew.

That storm had caught them by surprise with flooding in the middle of the night, he told CNN. But after being told by the city that the levee could be overwhelmed, the family didn't hesitate to leave.

On Sunday, Bostic, who fled her Rocky Point home the day before, learned she and her family got out just in time.

Her home, about 200 yards from the river bank, was submerged, and the water was still rising.

Nearly 20 years after Bostic lost almost everything to Hurricane Floyd, Florence would also force her to start over.

It's not over

On Sunday, two more deaths were confirmed in South Carolina.

Hundreds upon hundreds had been rescued in the Carolinas. There were at least 170 patients in four medical shelters across the state, and officials believed more would be on their way as the rescues and flooding continued throughout the day.

Floodwaters from Hurricane Florence inundate the town of Trenton, North Carolina, Sunday, September 16.

Pender County, North Carolina officials said they had received 300 calls for help by Sunday. Rescue attempts and other essential services were hindered by a lack of fuel.

Gov. Cooper accompanied the Coast Guard on a flyover of flooded areas in North Carolina. He said he saw significant flooding in the farmland of Jacksonville and throughout Onslow County.

In New Bern, where the drama of Friday morning had significantly diminished, the governor saw boats washed up in town and significant debris.

Flying over Fayetteville, he said, "it was stark to see the raging Cape Fear River, and you knew it was rising and you could see these vulnerable communities."

A sailboat is shoved up against a house and a collapsed garage Saturday, Sept. 15, 2018, after heavy wind and rain from Florence, now a tropical storm, blew through New Bern, N.C. (AP Photo/Steve Helber)

"We've got a tall task ahead," Cooper said.

The rain had slowed a little in Fayetteville, but officials there worried that would lure residents into a false sense of security and prompt them to make their way back.

"We're going to get hammered," said Kevin Arata, the city's director of communications.

"The worst is still yet to come."

CORRECTION: This story has been updated to give the correct strength of Florence at the storm's peak.