The three officers from the drug and crime prevention task force in Thanh Hoa Province were patrolling the border in Thuong Xuan District that afternoon when they spotted a suspicious-looking man with a bag. 

As they stopped the man and checked him, they were ambushed by another man hiding in the forest nearby. The three shot back but could not catch the two men, who fled toward Laos.

All three officers were injured in the shooting. They managed to collect the bag the man had carried, which contained 12,000 synthetic drug pills.

Major Vi Van Nhat, 36, died in hospital that evening due to loss of blood. Captain Vu Xuan Phuong and Sub Lieutenant Nguyen Binh Minh are still in hospital.

A manhunt has been launched for the smugglers. 

Vietnam is a key trafficking hub for narcotics from the Golden Triangle, an intersection of Laos, Thailand and Myanmar, the world's second largest drug producing area after the Golden Crescent in South Asia.

Vietnamese authorities deal with around 20,000 cases involving drugs every year and arrest around 30,000 people. The country has some 250,000 registered users, but the actual figures are thought to be much higher.

While heroin has long been common among drug users, the use of synthetic drugs like meth and ecstasy has been rising of late, especially among partying youth.