It was the second shooting in less than a week at the medical center located next to Interstate 90 in downtown Spokane.
Police say no one was injured in the incident and the prisoner is back in custody.
Police identified the prisoner as 26-year-old Cameron A. Trevino. He was arrested earlier this month for assault with a firearm and unlawful possession of a firearm. Police say Trevino will likely face additional charges because of Monday's incident
Last Tuesday, a man killed his wife and himself on the campus of Deaconess Hospital.