The South Korean company that owns the cargo ship that capsized off the coast of Georgia says it's grateful to everyone involved in the rescue of four crew members.

In a statement, Hyundai Glovis Co. Ltd. said the rescue of the crew members was "deeply appreciated."

The statement added that the company's staff is also "fully engaged" with agencies that are focused on limiting any damage to the environment.

The Golden Ray flipped on its side and caught fire as it left Brunswick, Georgia, with more than 4000 vehicles inside.

Earlier, Coast Guard rescuers pulled four trapped crew members from the ship, finding them alive more than a day after the vessel overturned.

The rescue followed nearly 36 hours of work after the Golden Ray, a giant ship that carries automobiles, rolled onto its side as it was leaving Brunswick, bound for Baltimore.

In the hours immediately after the accident, the Coast Guard lifted 20 crew members into helicopters before determining that smoke and flames and unstable cargo made it too risky to venture further inside the vessel. Officials were also concerned about the stability of the ship, which was carrying 4000 vehicles.

That left responders looking for the remaining four crew members. At first, Reed said, rescuers were not sure whether the noises they were hearing inside were some of the vehicles crashing around. But they later grew confident that the taps were responses to their own, indicating someone was alive inside.

"It was outstanding when I heard the news this morning that we had taps back throughout the night," Reed said, saying it helped lead rescuers to the right place on the 656-foot (200m) vessel, and provided motivation.

"They were charged up knowing the people were alive.”

Rescuers landed on the side of the Golden Ray and rappelled down the hull. Lt. Lloyd Heflin, who was co-ordinating the search, said they found three men in a room close to the propeller shaft, near the bottom of the stern. 

Responders began drilling, starting with a 3-inch (7.5cm) hole. Coast Guard officials brought the ship's chief engineer, who had earlier been rescued, out to the ship to translate, and found the three men were "on board and OK”, as Heflin put it.

Reed said rescuers passed food and water through the hole to the men. It also provided fresh air to the propeller room, which Reed said was even hotter than outside, where the high was 93F (34C).

Responders set up a tent on the hull and began drilling additional holes, eventually making an opening large enough to insert a ladder and help the men climb out.

"It was like connect-the-dots," Reed said of the hole, which grew to 2 feet by 3 feet (0.6m by 1m).

The Golden Ray was stuck in the shipping channel, closing one of the busiest US seaports for shipping automobiles. One ship was unable to leave port and four more were lined up outside waiting to come in, according to ship-tracking website Marine Traffic.