CHICAGO (CBS) — At a news conference to discuss the shooting of a Chicago police officer that took place Tuesday morning, Police Superintendent Eddie Johnson revealed the timeline of events of the deadly shooting at Mercy Hospital.

CPD officer Samuel Jimenez, Dr. Tamara O’Neal and pharmaceutical resident Dayna Less were killed in the incident. O’Neal’s former fiancee Juan Lopez shot all three. He is also dead. The Medical Examiner on Tuesday afternoon said Lopez was shot once in the stomach and then shot himself in the head.

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“He came to the hospital yesterday and confronted the doctor out in the parking lot,” Johnson said. “He came over there because she had broken off their engagement and he wanted his engagement ring back.”

It was Dr. O’Neal who called 911 during the altercation with Lopez in the hospital parking lot and said he had a gun.

“He shoots her (O’Neal), runs into the hospital as two females were getting off an elevator, had nothing to do with anything, he turns and starts shooting at them. That’s where he killed the one female (Less),” Johnson said. “He comes back out of the hospital and that’s when he engages police officers.”

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Johnson said Lopez fired at the squad cars then he ran back into the hospital.

“He was down a hallway and he was playing peek-a-boo with the officers firing down the hallway. He fired, the officers fired. What we do know is that he was struck twice,” Johnson said. “It’s only fair to assume that one of our bullets struck him and perhaps he discharged his own weapon.””

The Civilian Office of Police Accountability (COPA) confirmed that Lopez died of a gunshot wound to the abdomen with a self-inflicted gunshot wound to the head.

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Johnson said he believed a 9mm handgun was used by Lopez. A spokesperson for CPD said the weapon was purchased legally at a suburban gun shop.