Maj. Donald Ells had heard reports of flooding around Nichols, S.C.

But when Ells, an aerial photographer in the Maryland Wing of the Civil Air Patrol, flew over the hurricane-ravaged town this week, he saw it was almost completely submerged.

"They didn't know the overall devastation of it until we were able to provide those photos back to county planners and FEMA," Ells said on the tarmac at Martin State Airport on Tuesday. "All of the roads in and out of this area were completed flooded or washed out."

Ells' team is one of several from the Maryland Wing that have been drafted this week to help the Federal Emergency Management Agency assess the damage wrought by Hurricane Matthew.

The storm, blamed for hundreds of deaths in the Caribbean, was a category 1 hurricane when it made U.S. landfall in South Carolina on Saturday.

The Civil Air Patrol, a nonprofit, all-volunteer auxiliary to the Air Force, is called up after disasters to fly its distinctive red-white-and-blue planes and provide detailed aerial photographs to help authorities get a sense of how widespread problems are.

It's one of several missions the organization fulfills. Founded in 1941 to aid the military during World War II, the Civil Air Patrol started out by providing courier services, watching the borders and guarding the coastline against submarines.

During the Cold War, the organization took radiological air samples after atomic bomb tests and trained to assist authorities after a nuclear attack.

Now members participate in search-and-rescue efforts, keep an eye on boaters on the Chesapeake Bay, and respond to natural disasters.

Members aren't paid to go on missions, so they have been rotating in and out of the flooded regions. Ells and two other members returned to Maryland Tuesday after two days; they are to be replaced by a fresh crew later in the week.

Some members of the Maryland Wing were headed Tuesday to North Carolina, which saw some of the worst flooding.

In South Carolina, the Civil Air Patrol flew along rivers first, then followed a set of grids to map entire counties, to take pictures to share with federal and state officials for analysis.

Col. Jerry Weiss, vice commander of a group of state level wings stretching from Delaware to South Carolina, oversaw the operation from a command post at the Columbia airport. On Monday alone, he said, crews flew 20 sorties, and delivered critical information.

"When we discovered the one town under water they started moving their swift-water people in that direction," he said.

Nichols sits near the confluence of the Pee Dee and Lumber rivers. Just after the Maryland crew flew over the town, military helicopters arrived. It turned out 150 people were stranded and had to be evacuated. The waters aren't expected to recede before Friday.

Maj. John Ralph, an engineer at Northrop Grumman, zipped along at 130 miles per hour, just 1,000 feet above the ground. That's too low for autopilot, meaning he had to concentrate for hours on end.

It's an exhausting way to fly, Ralph said, but it gives the photographer an excellent view.

"From 1,000 feet you can pick out people," he said. "If it was somebody you know, you might actually recognize them."

It's also easy to get a sense of the scale of the destruction caused by the storm. The hurricane left at least 30 people dead in the United States and damaged thousands of homes.

"You're always focused on flying, but it's hard not to feel quite a lot of sympathy for people whose houses you see that are completely wiped out," Ralph said.

Today the Civil Air Patrol has 56,000 members nationwide and a fleet of 550 aircraft. The Maryland Wing has 1,400 members and operates about a dozen aircraft.

While the Civil Air Patrol has a military structure and members wear uniforms, it is not considered a part of the military in the way the National Guard is.

Officials emphasize the professional level of training that their pilots and aircrews receive, but say that because they are unpaid they can operate for a fraction of the cost of police or military aircraft.

Maj. Julie Holley, a spokeswoman for the Maryland Wing, says it takes a particular kind of person to be willing to drop their job and family and head out to a disaster zone to spend grueling hours doing unpaid work.

"I think the average member in Civil Air Patrol is a little crazy," she said. "We're obsessed with volunteering."

The Associated Press contributed to this article.