The South Korean coastguard shot and killed the Chinese skipper of a fishing boat Friday in a confrontation in the Yellow Sea, triggering an angry protest from Beijing.
A coastguard spokesman said shots were fired as the vessel was boarded for illegally fishing in South Korean territorial waters, around 80 miles (130 kilometres) off the western island of Wangdeung.
"Dozens of Chinese sailors attacked our officers with knives and beer bottles," said Choi Chang-Sam, chief of the Mokpo Coastguard Station.
"It was a dangerous situation. One officer fired a warning shot but they did not stop. So he fired several more rounds," Choi said, adding that five coastguard officers needed treatment for injuries.
The Chinese captain was taken to a hospital in Mokpo on the mainland where he was declared dead on arrival.
An emergency room staffer at the hospital told AFP that X-rays had shown a bullet lodged in his chest.
"His lungs were full of blood", the staffer said.
The Chinese foreign ministry reacted angrily to the incident and urged immediate action.
"We are deeply shocked and strongly dissatisfied with this violent law enforcement activity," ministry spokesman Hong Lei told reporters.
"We urge (South Korea) to immediately investigate this case, bring those accountable to justice, and inform China of the result of the investigation in a timely fashion," Hong said.
The South Korean foreign ministry sent its condolences to the dead man's relatives but argued the root cause of the accident was in illegal fishing by Chinese vessels.
"We would like to make it clear that... the accident took place... as Chinese fishermen reacted with violence to our coastguard's legitimate enforcement of laws (regarding) illegal fishing," it said in a statement.
Illegal fishing by Chinese boats is common in South Korean waters, and scores of vessels are seized every year.
In an incident two years ago, a 44-year-old Chinese fisherman was fatally wounded by a rubber bullet after South Korean coastguards boarded his ship, which was suspected of fishing illegally.
In 2011, a coastguard officer was stabbed to death in a struggle with Chinese sailors.