Sabina Shoal is currently home to one Philippines Coast Guard vessel and many Chinese vessels (Coast Guard and Maritime Militia). The shoal is claimed by both states. Recently there have been several clashes between China and the Philippines over the feature. It is speculated that the PRC has decided to block the Philippines from reinforcing the solitary vessel. The US is a treaty ally of the Philippines.
'killed' requires an physical act, specifically from one of the other countries mentioned in the question. In other words it doesn't count if someone dies for any other reason or they die in a way where it could be reasonably deemed that their own country killed them). It would count if another country took some action that clearly led to a death, ie a ship was sunk and survivors were not rescued.