Three crew members are believed to have died and two have serious burns following a fire onboard a Korean fishing boat in the Southern Ocean.
A further five crew have less serious burns, the Rescue Coordination Centre (RCCNZ) said.
The Jung Woo 2, carrying 40 crew, issued a mayday overnight, the RCCNZ said.
The 51-metre ship was in the Ross Sea, about 2000 nautical miles (3704km) south east of New Zealand and about 600km north of McMurdo Station.
The distress call was picked up by another Korean fishing boat, the Hong Jin 707, which was now alongside with the Jung Woo 3. They had evacuated the crew.
The RCCNZ said the fire was believed to have started in the vessel's accommodation block and was still burning. The ship appeared to be sinking.
Earlier search and rescue mission coordinator Dave Wilson said the fire had been reported as "out of control".
The rescuing vessels say they are unable to leave their current location due to ice and fog conditions and plan to transfer the injured seamen from the Jung Woo 3 to the US research vessel Nathaniel B. Palmer, which is steaming north to meet them.
The Nathaniel B. Palmer has suitable medical facilities on board and, after medical assessment, may sail to McMurdo Base to put the injured seamen ashore for further treatment and possible evacuation to New Zealand.
A number of other vessels are also responding and have been asked to rendezvous with Jung Woo 3 and the Hong Jin 707 to board the uninjured crew, as the two vessels are unable to proceed with the significant numbers of extra people on board.
The weather in the area currently is clear, with light winds, although a low is expected tomorrow.
The Jung Woo 2 was built in 1985 by Kanasashi Heavy Industries in Shizuoka, Japan, and originally named the Koryo Maru 32.
It is a longliner which fishes for Patagonian Toothfish, rays and crabs in the Antarctic Ocean. It has a gross registered tonnage of 489 and can carry up to 2.749 tonnes of catch.
The ship is owned by the Sunwoo Corporation of Korea.
The mayday call is the second from a ship fishing near Antarctica in a month. Last month the 48-metre vessel Sparta, with a crew of 32 aboard, ran into trouble after hitting ice in the Ross Sea.
The ship was stuck there for 12 days while repairs were made. It received help from another fishing boat and a Royal New Zealand Air Force plane dropped supplies and a pump. The Sparta returned to Nelson yesterday.
On December 13 2010, the No 1 Insung, a 31-year-old Korean toothfish longliner with Vietnamese crew operating out of Bluff, sank in the same area with the loss of 22 men.
In February last year a Norway-flagged yacht, Berserk, sank north of Scott Base, forcing HMNZS Wellington, an off-shore patrol boat, into a lengthy and dangerous search. Three men died in that sinking.