WATCH: 4 dead, including cop and hospital workers after shooting in Chicago

WATCH: 4 dead, including cop and hospital workers after shooting in Chicago

Transcript for 4 dead, including cop and hospital workers after shooting in Chicago

We’re going to turn now to the latest on that deadly shooting at a hospital in Chicago. Three people killed including a 28-year-old police officer who was responding to calls of an active shooter when he was attacked. The gunman is also dead. ABC’s Alex Perez is on the scene at mercy hospital with the latest. Good morning, Alex. Reporter: Good morning, Michael. Authorities say Dr. Tamara O’Neal had just wrapped up her shift here at the hospital and was walking out when she was confronted by her ex-fiance who was armed with a gun. Horrified doctors and nurses rushed out with their hands up evacuated from mercy hospital in Chicago as a gunman goes on a rampage. 10-1, shots fired. Reporter: The chaos beginning at 3:30 Monday afternoon in the hospital parking lot. That’s when authorities say the suspect, identified by our ABC 7 Chicago I team as 32-year-old Juan Lopez, armed with a gun in his waistband shot and killed his former fiance Dr. Tamara O’Neal. According to our affiliate WLS, the two seen in this photo posted to social media were supposed to be married in October but broke up in September. I had to fall to my knees because it started instantly like a battle, a gun battle. Reporter: The chilling sounds of gunshots caught on cell phone. Holy . Oh. The gentleman turned around and shot three times in her chest then once she fell to the ground he stood over her and shot her three more times. You witnessed all of this? Yes. Reporter: The gunman then takes his rampage inside the hospital. The P.A. System announcing that there is a shooter on the loose. The hospital goes into lockdown as doctors scramble to protect their patients. We just turned and started running towards the front of the hospital. It was chaos. It was just mass chaos. Once he entered he just started shooting random. Reporter: Samuel Jimenez who rushed to the scene killed in the lobby. They ran towards the gunfire. So they weren’t assigned to that particular call but they went. Because that’s what we do. Reporter: 25-year-old pharmacy tech Dayna les was just emerging from the elevator when the gunman fires at her killing her. Another officer responding to the scene also shot by the gunman but saved after the bullet struck the officer’s holster and lodged in his weapon. Overnight the hospital remembering Dr. Tamara O’Neal as a wonderful doctor who was devoted to her patients and to church. Officer Jiminez was actually in this area when he heard the call for help and was one of the first officers to respond on the scene. Michael. And, Alex, the officer that was killed, he had just joined the force. Reporter: Yeah, that’s right, Michael. He actually joined the force about two years ago but had just recently in August finished a probationary period and become a full-fledged officer. He leaves behind his wife and three young children. Michael. Thank you, Alex. Just heartbreaking. We move to the breaking news.

This transcript has been automatically generated and may not be 100% accurate.

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