Police in Hai Phong asked prosecutors to press charges against a local company, on Tuesday, after they discovered a large cache of guns and grenades.
The weapons were found in the director's office during an investigation of a gunfight at Anh Binh Minh, Ltd. last Saturday.
Three guns have been seized along with a grenade, 20 bars of explosives and many bullets and detonators.
Police said that last week, Luu Van Toan, 44, drew a gun from his trousers and fired shots at more than 100 people driving cars and motorbikes, on Saturday. Police said the crowd was chasing Toan and asking to see the company director Nguyen The Nghiem.
Toan was never an official employee of the company but had some personal relationship with Nghiem. He was once charged with "deliberately causing injuries to others."
He was still holding his gun and a grenade when the police arrived at the office.
A further search turned up a gun and bullets in Nghiem's office.
Investigators said the company might have borrowed money from the mob that Toan fired upon to trade wood. They believe that the group had sent people to collect the money.
It's not been clear which business the company is investing in.
Police have detained Toan and continue to investigate the matter.