Security officers at Tan Son Nhat Airport in Ho Chi Minh City on Wednesday night discovered a gun and 40 bullets inside a package bound for Hanoi.
The revolver and bullets were hidden inside one of seven packages of goods, which weighed a total of more than 100 kilos, said authorities. The packages were about to be loaded onto a Jetstar Pacific plane.
The sender, a company named TDNT in the city's Tan Binh District, claimed that the goods were clothes and electronic parts.
Police say they are looking into the case.
This is the first firearm discovery on a domestic flight this year.
Last year, dozens of similar cases were detected by security officers of Tan Son Nhat Airport.
A year ago, officers at the airport discovered disassembled parts of a rifle hidden in an express mail package bound for Hanoi.
In an earlier case in 2014, they even found a grenade and a rifle put inside a guitar being sent to the northern city.