In some cases the reported symptoms could be attributed to riot control agents. but the majority of attacks suggest an unknown type of nerve gas or a combination of lethal agents. The reported symptoms were strikingly similar to those reported in Yemen. No confirming medical or physical evidence was obtained by the team. Samples of "poison gas residue" claimed by the HMong to have been collected at the sites of two attacks were chemically analyzed. but results have been inconclusive. probably due to the age of the samples. An interesting report was obtained from one refugee. Several hours after an attack on his village. in September 1978. Pathet Lao soldiers wearIng masks entered the village. rounded up the survivors (1520) and gave them Injections.