Santichai Khiangklang has been charged in Helena with assault with a weapon.
Helena Police arrested Khiangklang on Sunday night.
Court documents allege that the 26 year-old man entered a business on the 600 block of Last Chance Gulch to confront an employee in a dispute involving a woman.
Witnesses say the suspect – wearing a handgun in a holster – approached the other person in an "aggressive manner" and unbuckled the weapon.
When the two individuals got into a fight, the gun fell from the holster to the floor.
Several people said they were afraid they’d be shot.
Following his arrest, Khiangklang’s blood alcohol was measured at .188, twice the legal limit to drive.
He told police that he had consumed two beers before the incident.
Bond in the case has been set at $25,000.