A pilot aboard an Asiana Airlines cargo plane that crashed Thursday in waters off a southern South Korean resort island reported a fire just before losing contact with air traffic workers, an official said.
The pilot yelled "Cargo fire!" and "Emergency!" about 10 minutes before the plane disappeared from radar screens, according to an air traffic official who declined to be named because the investigation was ongoing.
The plane also signaled an emergency to Jeju International Airport on the resort island, where it was trying to land, the official said.
The South Korean pilot, identified by the airline as Choi Sang-ki, was flying a Boeing-747 with a co-pilot, transporting computers, semiconductors, resin solution and paint among other items to Pudong in China, the airline said.
Asiana Airlines said the cargo had been loaded in line with international air transport regulations.
Five coast guard patrol boats and four helicopters searched the area for signs of the pilot and the co-pilot, Jeju coast guard spokesman Choi Kyu-mo said.
The coast guard recovered part of a wing with an Asiana Airlines logo on it, life jackets and parts of a pilot seat, the coast guard said in a statement.
The plane took off from South Korea's Incheon International Airport, west of Seoul, according to the airline.
Asiana officials got a report early Thursday morning from the pilot that the plane was having mechanical difficulties and would try to make its way to the Jeju island's airport, said Jason Kim, a spokesman for Asiana.
Officials then lost contact with the plane and asked the South Korean coast guard to investigate, Kim said. The airline also sent its own emergency specialists to the area.
South Korea has been lashed with extraordinarily heavy rain this week, with landslides and floods killing dozens and causing havoc. Kim said it was unclear whether the weather was a factor.
Coast guard officials said there was no rain in the area but stronger-than-normal wind.
North and South Korea are in a tense military standoff across their heavily armed border, but there was nothing to indicate that the crash had any military connection.
Asiana Airlines was in the news last month when two South Korean marines fired rifles at an Asiana plane carrying 119 people.
South Korea's military later apologized, saying the marines mistook the plane for a North Korean military aircraft. The military said it planned to strengthen training so troops can better distinguish civilian planes. Officials said the plane wasn't in range of the rifle fire.
Associated Press writers Foster Klug and Hyung-jin Kim contributed to this report.