Two members of staff killed in a shooting at a Chicago hospital that left four dead, also including the gunman and a police officer have been identified.

Emergency room physician, 38-year-old Dr Tamera O’Neal, was described as a fascinating, hard-working person.

Police said Ms O’Neal was confronted in the hospital parking area by the gunman, with whom she had been in a domestic relationship.

Witnesses said the man shot her and she fell to the ground. The gunman then stood over her and shot her again.

Mercy Hospital officials said 25-year-old pharmaceutical assistant Dayna Less, who was in training to become a pharmacist, was also killed.

According to police Superintendent Eddie Johnson, the woman was shot as she stepped from an lift. She was a recent Purdue University graduate.

Also killed was 28-year-old Chicago Police Officer Samuel Jimenez, the father of three children.