REDLANDS, Calif. (KABC) -- A bar employee and an off-duty deputy stopped what could have been a major tragedy by disarming a man brandishing an AR-15 semi-automatic rifle in Redlands.Redlands police said 36-year old Gilbert Arellano had reportedly been drinking Saturday at a birthday party before going to another bar at 18 E. Citrus Ave., where he continued to drink.Arellano got into an altercation with other customers at that bar. Police said he left the bar and went to his home in the 200 block of Nordina Street, where he retrieved an AR-15 semi-automatic rifle and a loaded 30-round magazine.As he returned downtown early Sunday morning, Arellano confronted three people in a parking lot and pointed the gun at one of them in a threatening manner, investigators said.Arellano then walked into the entrance at 19 E. Citrus Ave. holding the weapon in plain sight, authorities said. That's when an employee of The Underground bar, one of the businesses that shares the Citrus Avenue entrance, stopped Arellano and attempted to take the gun away from him. An off-duty San Bernardino County sheriff's deputy also arrived on scene to help after learning there was an armed man at the establishment. The two held Arellano until police arrived.Arellano was arrested on suspicion of attempted assault with a deadly weapon. Police determined that Arellano had additional weapons registered to him and, by court order, was not allowed to possess any guns. On Sunday afternoon police served a search warrant on his home where they confiscated additional weapons.If you have any relevant information about this case, you're urged to contact Redlands Police Dispatch at (909) 798-7681 ext. 1.