(ATTN: UPDATES throughout; CHANGES headline)
WASHINGTON, Sept. 9 (Yonhap) -- All four South Korean crew members trapped inside a listing vessel off the U.S. east coast have been confirmed alive, the U.S. Coast Guard said Monday.
Their conditions are unknown, but response crews will drill a hole in the ship to deliver supplies, it said in a tweet.
The Coast Guard and salvage crews are "developing an extraction plan to safely rescue the 4 #GoldenRay crew members. This is a slow, but safe process," it added.
The crew were the only ones left inside the Golden Ray after the cargo vessel flipped onto its side as it left the Port of Brunswick, Georgia, on Sunday.
Twenty others were rescued. The exact cause of the accident is yet unknown.
Contact was made after rescuers drilled a hole into the side of the ship and inserted equipment to check the air condition and send signals, a South Korean official at the consulate general in Atlanta, Georgia, told Yonhap News Agency earlier, quoting a Coast Guard spokesman.
"They received signals (from the crew members) at regular intervals of 20 to 30 minutes," he said.
The Koreans are presumed to be caught in the engine room of the car transport vessel belonging to Hyundai Glovis Co., a logistics unit of South Korea's Hyundai Motor Group.
The 71,178-ton, Marshall Islands-flagged ship listed heavily portside in waters 12.6 kilometers away from the port.
The South Korean government has sent a rapid response team consisting of eight people, including three from the foreign ministry in Seoul.