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,

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.

A memorial is growing as a Pennsylvania community mourns the loss of a police officer on Saturday. The officer was killed in the line of duty when a gunman opened fire inside the UPMC York Memorial Hospital.