On Oct. 15 they raided Lucas Palace club on Mac Thai To Street, Cau Giay District, where 16 people were gambling for stakes of as much as VND20 billion (US$825,400).
The Ministry of Public Security said Sunday 11 others are under investigation for organizing the gambling.
Dao Anh Dung, 31, and Tran Xuan Minh, 33, were in charge of running the club.
Dung took people who wanted to gamble to the third floor, while Minh would direct those who wanted to play poker for entertainment to the second.
Vietnamese nationals looking to gamble had to first be regulars on the second floor, while foreigners could go to the gambling tables right away.
The club collected 5% of the total stakes.
Dung used to get 70% of the profits from the gambling and Minh the rest until he brought more customers and increased his share to 50% since September.
Vietnam bans its citizens from all kinds of gambling. Several casinos are opened for foreigners but have to be registered for the operation.