A suicidal gunman opened fire at a Nevada hospital, killing one person, critically wounding two others and sending police on a door-to-door search at the sprawling complex.
The wounded, including a woman doctor, were undergoing surgery.
The gunman killed himself after the shooting, which Reno deputy police chief Tom Robinson said did not appear to be random.
"I wouldn't say they were targeted, but I don't think it was just random," he said outside the medical building on the Renown Regional Medical Centre site.
Mr Robinson said he did not know how many shots were fired or what type of weapon was used but all three victims and the gunman suffered some kind of gunshot wound and were in the same general area on the building's third floor.
"As far as the suspect goes, we still don't have a solid identity yet but we are working several leads on who he is," Mr Robinson said.
The shooting happened yesterday at the Centre for Advanced Medicine, a modern structure connected by a second-floor walkway to the main hospital and a car park.
Mr Robinson said there were about 100 people in the building when the shooting was reported at 2.05pm local time. Officers entered three to five minutes later and made "a systematic search, floor to floor, room to room".
"On the third floor of the building they located two people down and located two people injured and evacuated the injured parties," he said.
The medical centre was sealed off as police rushed to the scene and victims were treated by doctors at the hospital. More than 30 police cars, including SWAT team vehicles, surrounded the complex and closed off a three-block area near central Reno.
State senator Debbie Smith was at Renown for an appointment and was trying to leave a nearby building when the shooting started.
"I encountered some SWAT team guys, they said nobody was leaving," she said. "A police officer was at the door and said I couldn't go out there."
The medical centre posted a notice on its website less than two hours after the shooting saying operations had returned to normal at the main hospital but police were still investigating the shooting. About 24 witnesses were taken to police headquarters for interviews.
At least one person was taken by ambulance from the building where the shooting happened to the Renown hospital's emergency room, less than a block away.
Governor Brian Sandoval said on Twitter that he and his staff were monitoring the situation and his thoughts and prayers were with those affected by the tragedy.
The shooting came nearly two months after a 12-year-old boy opened fire at an area middle school, killing a maths teacher before taking his own life. Two other students were treated for their injuries at Renown Regional Medical Centre, the largest hospital in northern Nevada.
The centre has treated victims of other recent tragedies in northern Nevada, including a crash at a Reno air race in 2011 that killed 11 people and a rampage at a Carson City restaurant the same year that killed three Nevada National Guard members.