Park rangers came across a group of four poachers near a forest in Dong Nai Province's Tan Phu District on Monday night. On being detected, the poachers pepper-sprayed the rangers and the latter fired warning shots in the air.
The poachers managed to escape, but left behind four bags with around 140 kg of gaur meat and bones and some equipment.
The gaur they had killed weighed around 200 kg, according to park authorities.
A 2008 census found around 300 of the animals in the park and the Dong Nai Culture Nature Reserve.
The gaur (Bos gaurus), the world’s largest wild bovine, is classified as a vulnerable species in the International Union for Conservation of Nature Red List of Threatened Species, and protected in Vietnam.
It is illegal to hunt, kill, possess, capture, transport, or trade protected animals, and penalties include 15 years in prison and fines of up to VND15 billion ($645,000), but poaching and wildlife trafficking remain significant problems.