The man who authorities say entered a Pennsylvania hospital with zip ties and a pistol over the weekend had recent contact with the hospital's intensive care unit, where he took staff members hostage and was killed in a shootout that left a police officer dead and others injured.

Investigators are still trying to determine why a man targeted a Pennsylvania hospital, taking workers inside the intensive care unit hostage and holding one staff member at gunpoint as her hands were bound by zip ties.

A gunman who held medical staff hostage before killing a police officer and wounding five others at a hospital in south-central Pennsylvania Saturday is believed to have visited the facility in the days leading up to the incident,