When Seattle Police officers recovered a stolen vehicle in the Chinatown-International District on Saturday, they also arrested an Auburn man with an illegally manufactured firearm.

According to the Seattle Police Department, before 4:30 p.m. Dec. 5, officers patrolling the Chinatown-International District spotted a stolen Mazda truck in the 800 block of South King Street, under the I-5 overpass.

Police detained the two occupants of the vehicle and a third man who had been standing outside the truck, leaning on the driver’s door.

When officers contacted the man outside the truck, he was holding a homemade firearm. According to the SPD, the man admitted to having recently fired a test shot with the taped-together weapon — known as a slam gun — under the overpass. Officers arrested the man for unlawful discharge of a weapon and possessing an unlawful firearm and booked him into the King County Jail.

Police interviewed and released the female passenger at the scene and are still investigating the male driver.

The Auburn Reporter is withholding the man’s name because the King County Prosecutor’s Office has yet to charge him with a crime. He is being held in King County Jail on $10,000 bail.