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,

Authorities say a shooter entered UPMC Memorial Hospital's ICU and took staff members hostage before he was killed by police in a shootout.

A police officer died and others were injured in what local officials described a hostage crisis involving a man with a gun and zip ties.