Police locked down a Denver hospital complex Friday amid reports that gunshots were fired and a man was seen carrying a rifle on the grounds.
A room-by-room search of Rose Medical Center continued into the evening. No arrests or injuries were reported.
Investigators did not confirm if any shots had been fired.
Police later lifted orders for people to shelter in place at buildings near the hospital complex but urged those inside Rose Medical Center to stay in place while officers continued to investigate.
During the lockdown, police officers carrying long guns surrounded the facility east of downtown, and several roads were closed and blocked by patrol cars.
Armed officers climbed to the roofs of buildings.
An adjacent Veterans Administration hospital also was locked down as a protective measure.
The scene outside was calm by Friday evening.
Denver police Officer Tyrone Campbell said authorities received multiple telephone calls reporting shots had been fired in the area surrounding the medical center shortly after 4:15 p.m.
Authorities were looking for a suspect described as a white male in his mid-30s wearing a flannel shirt and a hat.