(CNN) -- The fatal shooting at a Reno, Nevada, medical building this week does not appear to be a random act of violence, police said without elaborating Wednesday.
Police identified the three victims and were waiting to release the deceased shooter's name until his next of kin was notified.
Dr. Charles Gholdoian, 46, was killed, and patient Shawntae Spears, 20, was wounded, Reno Deputy Police Chief Mac Venzon said at a news conference.
Dr. Christine Lajeunesse is in critical condition, but conscious, a spokeswoman for the city told CNN on Wednesday night.
Spears and Lajeunesse suffered single gunshot wounds. Spears also is in critical condition at Renown Regional Medical Center.
The investigation, which includes interviews with 29 witnesses, indicates the shooter walked past the front desk to a patient exam room area and fired five rounds from his 12-gauge shotgun. He later killed himself with the weapon, Venzon said.
The shooting occurred at the Urology Nevada office on the third floor of a medical building near Renown, leading investigators to believe it wasn't random, Venzon said.
Asked to explain, the deputy chief said the shooter passed the first and second floors, and making "his way to the third floor of the building would indicate to me this is not a random event."
He further said that it did not appear the shooter had a relationship with any of the victims, but the matter is still under investigation.
Police don't have a motive.
Kat Raco, an ophthalmic technician who works on the second floor of the Nevada Advanced Medicine building, told CNN that she heard at least two large booms and then the sound of scampering feet above her.
Raco said she and others in her office were seeing patients when the shooting occurred and first thought someone or something had fallen.
Police were there quickly, she said, telling them to lock the doors and not let anyone in.
About 10 minutes after that, more police escorted everyone on the second floor to a catwalk between the building and a parking garage. A plainclothes officer asked questions before staff was allowed to leave about 45 minutes after the shooting.
"The police handled it in the best way possible," Raco said. "They were very professional and calm. Everyone (in the office) stayed pretty calm."
Raco said there are no armed guards in the building.
The medical center describes itself as the only Level II trauma center in that region of Nevada and is home to the area's only Children's Hospital, its website says. The facility also offers the region's largest number of clinical research trials.
Last month, there was a hospital shooting in Wisconsin when police shot and wounded an armed man on the neonatal intensive care floor of a Milwaukee-area children's hospital, authorities said.
Milwaukee police had gone to the Children's Hospital of Wisconsin to arrest the man on a felony warrant and found him holding a child in the intensive care unit, authorities said. Instead of surrendering, the man took out a handgun and fled down a hallway, prompting police to shoot him.
CNN's Mayra Cuevas, Eliott C. McLaughlin, Chandler Friedman and Steve Almasy contributed to this report.