The incident occurred in Srisoonthorn at about 5:15am yesterday (May 6) after an argument over a blocked roadway escalated outside an ice factory.
According to reports, the van had been parked in front of the factory entrance for about seven to eight minutes, preventing ice delivery trucks from entering to collect ice as scheduled.
The ice delivery driver said he approached the van driver to ask him to move the vehicle, leading to a heated exchange between the two men.
Witnesses said the van driver later followed the ice truck to the factory. After briefly speaking with workers outside the premises, he returned to his van, retrieved a rifle and threatened the driver as well as nearby employees and bystanders.
Videos and photos of the confrontation were later circulated widely online.
Police said the suspect, identified as Somchai Sirimongkol, 60, later contacted Thalang Police and surrendered himself that same evening.
Officers led by Pol Lt Col Thapthai Leelanont and Pol. Lt. Col. Suchart Luecha questioned Somchai and inspected the firearm used in the incident.
Police confirmed the weapon was a legally registered CZ .22 calibre rifle.
Somchai reportedly told investigators he became enraged after being insulted with derogatory remarks about his parents during the roadside argument.
Police seized the rifle and the firearm licence as evidence at Thalang Police Station.
Mr Somchai has been charged with carrying a firearm in a city, village or public place without reasonable cause, police confirmed.
Legal proceedings are continuing. However, no mention has been made about any consequences for Somchai carrying a firearm in a public transport vehicle.