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 by zip ties.

The unease growing inside Nancy Duarte Matarese on Saturday quickly blossomed into full-on dread as she found herself being escorted to a small family room inside WellSpan York Hospital.

A West York Borough police officer and a gunman were killed in a shooting Saturday morning that injured multiple staffers at UPMC Memorial Hospital in York County, Pennsylvania, the district attorney said.