Seoul , South Korea ( CNN ) -- A South Korean coast guard commando was stabbed to death and another injured Monday after they boarded a Chinese fishing vessel they suspected of fishing illegally in the Yellow Sea , the coast guard and a South Korean news agency said Monday . The incident triggered a swift diplomatic response , with the South Korean Foreign Ministry calling in the Chinese ambassador to South Korea to protest , the Yonhap news agency reported . First Vice Foreign Minister Park Suk-hwan `` strongly demanded the Chinese government strictly clamp down on illegal fishing and the illegal acts of Chinese fishermen , '' the news agency quoted him as saying . South Korea said it had seized the Chinese ship and nine sailors aboard , Yonhap reported . A spokesman for China 's Ministry of Foreign Affairs said Monday that the country is `` closely following the case . '' `` China is ready to work closely with the ( South Korean ) side to handle the case properly , '' spokesman Liu Weimin said . `` The two countries had signed relevant fishery agreements . ... Competent authorities have taken measures to educate Chinese fishermen and management of outbound fishing boats to prohibit cross-border fishing and irregularities . `` At the same time , '' Liu added , `` we hope the ( South Korean ) side will fully protect the rights and interests of Chinese fishermen and provide them with due humanitarian treatment . '' The incident started after South Korean commandos boarded the Chinese ship . The captain of that ship `` suddenly broke a window pane on the ship '' and stabbed one commando several times with a piece of broken glass , Yonhap reported . That commando later died ; another was hurt . South Korean authorities took the ship toward the port at Incheon , west of Seoul . The Yellow Sea has been a point of contention for several Asian countries , most notably North and South Korea who have long disagreed on whose waters end where . The South Korean coast guard has stopped hundreds of Chinese boats this year on suspicion of illegal fishing in the sea . The waters , which are important fishing and crab grounds , are also frequently crowded with boats from China . And disputes over fishing rights have resulted in dozens of boat seizures . CNN 's Chi Chi Zhang and Tim Lister contributed to this report .
NEW : North Korea has seized the ship and its nine sailors . South Korea : The sailors are suspected of fishing illegally in the Yellow Sea . Members of the South Korean coast guard board a Chinese ship to investigate . One sailor on board stabs the fishermen , killing one , the coast guard says .