The gunman who held intensive care unit staff hostage at UPMC Memorial Hospital in Pennsylvania before killing a police officer and injuring five other people Saturday believed that more could have been done to save his wife,

A man who took hostages in a Pennsylvania hospital during a shooting that killed a police officer and wounded five other people highlights the rising violence against U.S. healthcare workers and the challenge of protecting them.

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.