A gunman shot to death a doctor outside a Chicago hospital on Monday before bursting into the facility and killing a woman and a police officer during an exchange of gunfire and dying in the shooting, officials said.
The shooter knew the doctor he shot outside Mercy Hospital, but once inside he fired randomly at people, Chicago Police Superintendent Eddie Johnson said at a news conference.
The shooting sent doctors and patients streaming out of the facility, some with their hands up as heavily armed police officers sought to secure the facility.
"The city of Chicago lost a doctor, a pharmaceutical assistant and a police officer, all going about their day, all doing what they love," Chicago Mayor Rahm Emanuel told reporters.
"This tears at the soul of our city. It is the face and consequence of evil," Emanuel said.
The police officer, Samuel Jimenez, died in an exchange of fire with the gunman after he entered the medical facility, Johnson said.
Twitter: Chicago Police confirm that the police officer shot this afternoon at Mercy Hospital has died at University of Chicago Hospital.
The gunman, whose name has not been released, also died, officials said. But it was not immediately clear if he shot himself or if he was struck by a police officer's bullet, Johnson said.
Another officer was spared injury when a bullet lodged itself in his holster, Johnson said.
In Denver, another shooting left one person dead and three others wounded on Monday. At least one suspect remained at large after the shooting on a downtown street corner.