An off-duty San Francisco Police officer reported an adult male suspect in possession of a handgun while aboard a San Francisco bound train held at the station. BART officers responded and detained the suspect as he was pointed out by the off-duty officer. A loaded .45 Caliber handgun was located in the suspect’s waistband by the officers, who then placed him under arrest for possessing the loaded handgun. A search of the suspect, incident to the arrest, revealed he was also in possession of narcotics and items consistent with the sales of narcotics. A sergeant responded to approve the arrest, debrief the suspect and perform a use of force investigation. Detectives were called upon to assist the investigative portion of the arrest. Subsequently, the suspect was booked into the county jail for the following charges: Possessing a loaded and concealed firearm, possessing a firearm with obliterated serial numbers, possession of Marijuana and Heroin for sales, being a convicted felon in possession of a firearm, possession of narcotics for sale with a previous narcotics possession conviction, and (narcotics) probation violation.