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,

Investigators are 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

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.