A cargo ship with a total of 13 Chinese and six Philippine crew members while heading to Singapore, asked for help after the ship started taking on water. South Korean coast guard responded to their calls and rescued all crew from the sinking cargo ship. Unfortunately the coast guard vessel capsized after rescuing the crew in distress and as a result three Filipino and two Chinese seafarers died.
The boat overturned while carrying 15 crew members rescued from the 5,436-tonne Malaysia-registered Shinline freighter near the southern island of Jeju. All the coast guard officers and 10 of the freighter’s crew were rescued unhurt by another coastguard vessel involved in the operation, but five seafarers perished during the incident. According to a South Korean spokesman high waves caused the coastguard boat to capsize.
Update 1: Oct. 21 2012
Korea’s Coast Guard reported on Saturday that it has begun salvage operations of its capsized boat. The Coast Guard boat capsized on Thursday, presumably due to high tides, during a rescue operation for sailors from a Malaysian cargo ship, resulting in the deaths of three Filipino and two Chinese sailors from the cargo ship.
Coast Guard officers said they began to salvage the sunken boat with a crane earlier in the day, and plan to inspect the wreckage to find the exact cause of the accident. Investigation is also under way into what caused the Malaysian freighter which, according to the investigators, asked for help after holes in its hull caused water to rush into the boat.
Sources: ABS-CBN, Pinoy Republic, Korea Times
Officer of the Watch 
[…] Officer of the Watch is reporting the S. Korean Coast Guard had rescued all 19 crewmen from a Malaysian Registered 5,436 ton freighter which subsequently sank, but one of the cutters, carrying 15 of the survivors capsized and five of the survivors (three Filipino and two Chinese) died as a result. The remaining ten survivors and the crew of the cutter were rescued by another cutter involved in the operation. […]