As winds began to whip his neighborhood in Port St. Lucie, Florida, on Monday, Brock told CNN he's still planning to ride out the storm at home.

"I'm prepared for this, I've got my children taken care of ... we're ready for this," Brock said. "Everything's pulled in the garage, we've got our storm shutters up, my daughter's got hers up, my son's got his up."

Brock is one of millions of residents in Florida, Georgia, and South Carolina who are or will be under mandatory evacuation orders as Dorian approaches. And he's not alone in deciding to ride out the storm.

Officials warned those living in evacuation zones to heed the orders, but many residents who spoke with CNN said they were struggling to make a wrenching decision: to flee the approaching storm or face potential danger by hunkering down at home.

That decision is becoming harder and harder as Hurricane Dorian creeps westward on an unpredictable path, with coastal residents throughout the southeastern US monitoring every minor change in direction -- and bracing themselves amid reports of "catastrophic" damage in the Bahamas.

Harry Brock is prepared to ride out Hurricane Dorian in his Port St. Lucie, Florida, home.

"It just tore my heart to see the destruction that they've been through over there," Brock said.

There's only one thing left to do as Dorian approaches the United States, he said.

"All we can do," he said, "is pray for our coastline."

For many, it's a difficult choice

To stay or go? It's a choice many coastal residents in the Southeast US will have to make in the coming hours.

Officials stress that evacuation orders shouldn't be taken lightly, and emphasize that people who stay may end up marooned if the storm hits and emergency crews can't get to them.

"If you are ordered to evacuate, you need to do that," Florida Gov. Ron DeSantis told residents Monday morning. "From Palm Beach County all the way up to ... the Florida-Georgia border, all those coastal counties have issued evacuation orders. And its important that residents heed those calls," he said.

"Get out now while you have time, while there's fuel available and you'll be safe on the roads."

In Florida's Indian River County, Maj. Eric Flowers said authorities are concerned about residents who refuse to evacuate. If those people encounter an emergency, first responders will not be able to help them if the storm gets too strong, he said.

"It's going to be difficult for us to get out to the barrier islands after the storm. ... This is a slow-moving storm, so we're concerned that those folks might get isolated out there for a time until Dorian actually passes and it's safe for our first responders to get out there to them," said Michele Jones, emergency management director for Martin County, Florida.

Jack and Violet Honey were sitting outside their mobile home in Port St. Lucie on Monday, waiting for the storm to make a move before they decide what to do.

"If the storm comes closer, we're leaving," Jack Honey told CNN. "If it turns and goes north, we're going to stick it out."

The couple is under a mandatory evacuation.

Violet Honey said she has a gut feeling things will be fine but leaves the evacuation decision to her husband. He said their car is packed and ready to go at a moment's notice.

Jack Honey says he and his wife will head southwest if they feel Dorian is threatening their home.

If need be, the couple plans to drive southwest, where Jack Honey thinks the storm won't have a major impact.

In Vero Beach, about 30 miles north, a mandatory evacuation is also in place. But that hasn't stopped crowds from coming to the beach to gawk at the ocean.

CNN has witnessed police reminding residents that they have been ordered to leave. But many people say they believe the storm will veer away and they plan to head inland if Dorian gets closer.

Experts say some residents don't want the hassle of loading their car and evacuating, while others may have a false sense of security or not realize they live in an evacuation zone.

Mary Gordon anxiously watched the water rising Monday beside a dock near her home in Daytona Beach, Florida.

Mary Gordon of Daytona Beach says she's worried about the storm but not planning to evacuate. "I see more scary things than I have in the past," she told CNN on Monday. "The water at the last ones was never this high this far ahead of the actual storm."

Already, Gordon said, Dorian seems unpredictable and scary.

"The water's higher than I've ever seen it before, even this close to a storm. It's already coming over the wall," she said, pointing at the shoreline.

Gordon says she's worried about damage the hurricane may bring, but she's still planning to ride out the storm in Daytona Beach.

"I've got an inside room that I feel safe in, no windows in it. It has never flooded. ... I'm not going to evacuate this year, because if I wait another few hours it's going to be too late anyway," she said. "If anybody's going to evacuate, they better be going in the next few hours, because otherwise you're going to get caught in it."

In Stuart, Florida, where many residents live in low-lying neighborhoods near two rivers and a canal, Kris Garrigus told CNN Monday that he was closing up his house and getting out.

Kris Garrigus, who lives near a canal in Stuart, Florida, told CNN he's evacuating because he's worried about flooding.

"Flooding is the main concern for sure," he said. "They release Lake Okeechobee, and then it comes up. And then if this thing hits on high tide, we're screwed."

Further north in Jacksonville, 85-year-old Adella Williams also said she was taking no chances.

She told CNN she's going to ride out the storm at a nearby school. It will be her third year in a row doing so.

While she's never had any damage to her home from storms, Williams said there's one thing she knows she doesn't want to do as Dorian nears: risk her life.

Florida mandatory evacuations

parts of St. Lucie County

Indian River County

St. Johns County, including the entire city of St. Augustine

parts of Brevard County, including barrier islands, Merritt Island and the Kennedy Space Center

parts of Palm Beach County, including the Jupiter Inlet and other surge-vulnerable areas along the Intracoastal Waterway

parts of Martin County, including barrier islands and Sewall's Point

parts of Nassau County

parts of Duval County

parts of Flagler County

coastal areas of Volusia County

in Osceola County, the Good Samaritan Village in Kissimmee

parts of Putnam County

In many of these counties the evacuations specifically mention those living in low-lying areas, RV parks and mobile homes.

At least seven Florida hospitals have begun evacuating or are making plans to evacuate, and nearly 100 nursing homes and assisted-living facilities along the state's east coast have been evacuated, officials said in a statement Monday

Outside Baptist Medical Center Beaches in Jacksonville on Monday, teams pushed stretchers carrying patients through a parking area where ambulances were waiting to transport them to sister hospitals. Evacuations of the facility began over the weekend, with more than 100 patients transported or discharged to safe locations, hospital president Joe Mitrick said.

"It's for patients' safety and our staff's safety. ... A lot of preparation has gone into this," he said.

Georgia mandatory evacuations

Georgia Gov. Brian Kemp has ordered mandatory evacuations from areas east of Interstate 95 in the following counties: Bryan, Camden, Chatham, Glynn, Liberty, and McIntosh.

Kemp urged residents to heed evacuation orders, warning that flooding after the storm hits might block first responders from reaching those who need help

"If coastal residents decide not to evacuate -- and I want to be very clear -- they will be on their own if first responders are unable to reach them," Kemp said Monday afternoon. "It's not worth it."

South Carolina mandatory evacuations

South Carolina Gov. Henry McMaster has issued evacuation orders for parts of Jasper County, all of Beaufort County, parts of Colleton County, all of Charleston County, parts of Berkeley County, parts of Dorchester County, parts of Georgetown County and parts of Horry County.