(KTXL) — More details were released Tuesday night about one of the weapons recovered from the scene of Sunday’s mass shooting.

Sacramento police said the weapon was a stolen handgun that was illegally converted to a weapon capable of automatic gunfire.

FOX40 spoke with retired Bureau of Alcohol, Tobacco, Firearms and Explosives expert Rick Vasquez who said the illegal components that turn handguns into automatic weapons often come from overseas or south of the U.S. border.

Vasquez said the converted handguns are very difficult for anyone to fire accurately.

“Many of these guns get shot the first time when they go out on the street and pull the trigger with a full magazine. So, there is no control, and you have indiscriminate firing from these firearms. Unfortunately, they have become extremely common,” Vasquez explained.

Vasquez said the parts used in the conversion are difficult to track because they’re smaller than a quarter.