The incident started from a land dispute between local men and two men from Ca Mau Province that border Kien Giang Province, home to Phu Quoc, police said Friday.
On Thursday afternoon, more than 50 people working for the Ca Mau men traveled to a land plot belonging to the Phu Quoc men in eight cars to settle their dispute, bringing along guns and machetes. On that land plot, many workers were building a villa.
As the fight escalated, the Ca Mau men opened fire, killing Phan Trong Hai, 24, and Nguyen Anh Thu, 26, and causing serious injures to four other people.
Footage from a security camera in the neighborhood showed there were at least 12 shots fired.
Kien Giang police are investigating the case further.