( CNN ) -- A court in China 's Yunnan Province on Wednesday rejected an appeal from six defendants convicted of killing 13 Chinese sailors , said the state-run Xinhua news agency . Last month , the Intermediate People 's Court of Kunming sentenced four of the men to death for the killings , which occurred in October 2011 on the Mekong River . They were also ordered to pay compensation of 6 million yuan ( about $ 960,000 ) . Read more : Chinese court sentences drug gang to death over river murders . One of the men is a drug lord identified as Naw Kham ; the other three were members of his gang , Xinhua said . Of the two other gang members , one received a death sentence with a reprieve and another was sentenced to eight years in prison . Thai authorities discovered the murder scene after boarding two Chinese cargo ships that had come under gunfire . They found nearly 1 million amphetamines and the 12 bodies , some with their hands bound . One sailor was missing . The men had been charged with homicide , hijacking , kidnapping and drug trafficking . The alleged gang was arrested in a joint operation by police from China , Laos , Myanmar and Thailand , according to the state-run China Daily . Five of the six men are from Myanmar , Thailand and Laos ; one is stateless , Xinhua said . Naw Kham 's gang colluded with Thai soldiers in the attack on the cargo ships , the Hua Ping and Yu Xing 8 , Xinhua said . Naw Kham had also directed several of his subordinates in the kidnapping of Chinese sailors and hijacking of cargo ships in exchange for ransom in early April 2011 , the court said . Read more : Opinion : Mekong River dam threatens livelihoods and ecosystems . CNN 's Elizabeth Yuan contributed to this report .
The court rejects the appeal by all six defendants . Two of the men had received life sentences . They were implicated in the December 2011 killings of 13 Chinese sailors .