there are new details coming in tonight about the horror that unfolded inside that hospital just a short time ago authorities came before the cameras describing what happened a gunman taking aim at an ER doctor his ex-fiancee and then going on a rampage targeting an officer and a pharmacist who just happened to be getting off an elevator ABC's Alex Perez in Chicago again tonight tonight the horrifying new details about the deadly rampage at Mercy Hospital in Chicago authorities say 32 year old juan lopez arrived just before 3:30 Monday afternoon to confront his ex-fiancee ER doctor Tamara O'Neill demanding his engagement ring back that's when police say Lopez shot and killed her Lopez then moving inside the hospital killing Chicago police officer Samuel Jimenez and pharmacy technician Dana less that poor woman that got got off an elevator and nothing to do with nothing and he shot police heroically facing off with the gunman as doctors fled with patients one officer struck in his holster his gun is stopping the bullet the gunman dead at the scene had those officers not engaged that that guy yesterday there's no telling how much loss of life we would have had tonight tributes to the lives lost the officer he meant as a husband and father of three Dana less his father says she was set to marry her high school sweetheart next year I was going to be giving a wedding speech instead of a eulogy and dr. O'Neill with a beaming smile on the day she found out she would be an emergency medicine physician her father spoke with her the night before she died and she said I love you those are the last words that she spoke to me and Alex Perez joins us live from the hospital again tonight and Alex this evening you've learned that the gunman actually had accusations of violent behavior in his past David he was dismissed from the Fire Academy after allegations he bullied female cadets and according to court documents his ex-wife accused him of threatening her and says he slept with a pistol under his pillow David Alex Perez our thanks to you hi everyone George Stephanopoulos here thanks for checking out the ABC News YouTube channel if you'd like to get more videos show highlights and watch live event coverage click on the right over here to subscribe to our channel and don't forget to download the ABC News app for breaking news alerts thanks for watching