Two Chinese ships were attacked on the Mekong River on December 9 . China 's Foreign Ministry says at least 20 sailors were killed in the attack . China says it 's working with Thai authorities to hunt down the pirates .
Two Chinese ships were attacked on the Mekong River on October 5 . China 's Foreign Ministry says at least 12 sailors were killed in the attack . China says it 's working with Thai authorities to hunt down the criminals .