Police didn't outline a motive but the new details could give a fuller picture of why the urology clinic was targeted.
Two other people were wounded.
Reno police also confirmed Thursday that the shooter was 51-year-old Alan Oliver Frazier of Plumas County, Calif.
Police say Frazier had a surgery in 2010 and claimed to have adverse symptoms because of it.
But it was not immediately clear if the unspecified procedure was performed at Urology Nevada, the site of the shooting on Tuesday, or if either of the two doctors who were shot had been involved in the operation.