Vietnamese authorities detained the 16 Chinese - 10 men, four women and two children - after they entered the country illegally in Quang Ninh province, the regional government said in a statement.
As guards checked their papers in a room at the Bac Phong Sinh border crossing, one of the Chinese grabbed an automatic weapon from a guard and began firing, the statement said. A standoff ensued as some of the men then holed up in the office, it said.
No other details were available. Independent media reporting is not allowed in the town.
Quang Ninh is opposite China's Guangxi province. Many Chinese traders and tourists enter Vietnam through the province.