Authorities say Montrose Police Sergeant David Kinterknecht was wearing a protective vest when he was shot and killed, but the fatal blast struck an unshielded area on his side.
Montrose County Coroner Thomas Canfield says Kinterknecht had turned sideways to move around a door and was hit under his left arm between the vest's front and back plates.
Two other officers were injured during a domestic disturbance call Saturday. Investigators say the gunman, 52-year-old Dennis Gurney, fatally shot himself.
Officers Rodney Ragsdale and Larry Witte were shot in the legs. Ragsdale is in good condition at a Grand Junction hospital and Witte was released Tuesday from a Montrose hospital.