The group entered Vietnam through the forest at midnight and was discovered by local authorities at Kem slope in Xop Pu village, Yen Na commune, Tuong Duong district.
Especially, they also carried AK rifles and grenades, and opened fire against the police in attempt to flee.
A Lao citizen, who has yet to be identified, was killed from a gunshot wound. Two other suspects escaped.
At the scene, authorised agencies seized three heroin bricks, along with 12,000 meth pills, a rifle, two grenades and 18 bullets.
The case is being further investigated.
One day earlier, the border guard force in the neighbouring province of Ha Tinh and authorised forces arrested two men who were smuggling 32 kg of methamphetamine and ten bricks of heroin from Laos to Vietnam.
Tran Xuan Thanh (born in 1988 in Yen Thanh district, central Nghe An province and living in Vientiane, Laos) and Vo Quoc Duong (born in 1977 and residing in Dien Chau district, Nghe An province) were caught red handed with 30 kg of methamphetamine.
Examining their car registered in Laos, the authorities found and seized an additional ten bricks of heroin and 2 kg of methamphetamine.
The arrested admitted that they transported the drugs from Laos to Vietnam for consumption.