Several people have been shot in a hospital in Chicago, police in the city have said.
Multiple people have been wounded, including a police officer, after an "active shooter" attack at a Chicago hospital.
Sources say the gunman first targeted a woman, who witnesses said was dressed in hospital scrubs, in the parking lot.
He said a police officer had been shot and was in a critical condition.
A police officer and at least one hospital employee are among the four in critical condition following the incident.
Shooting reported at Chicago hospital
As of 4:40 p.m., police secured the hospital and all patients are safe, according to hospital officials.
A Twitter user posted video of what appeared to be Chicago police officers searching the interior of the hospital - and a blood trail on the hospital floor.
"I turned around to my right and I see a man shooting someone on the ground, shot him multiple times".
Gray described the shooting as surreal, "like a movie scene".
Sue Jimenez, the manager of Kozy's Cyclery bike shop near the hospital, said she heard multiple gunshots separated by pauses. She said she saw officers shooting back and forth.
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