A patient opened fire at a hospital in Darby, Pennsylvania, on Thursday, killing a caseworker and grazing a psychiatrist in the head. That psychiatrist then helped stop the gunman by using his own weapon to wound him, authorities said. Police were called around 2 p.m. to respond to a shooting on the third floor of a wellness center at Mercy Fitzgerald Hospital. The building was then evacuated and placed on lockdown. The gunman has been identified as Richard Plotts, a patient who had been involved in previous incidents with staff. Hospital staff reported hearing loud arguing inside the office, then opening the door and finding the patient pointing a gun at the doctor (they then closed the door and dialed 911). The hospital has a policy barring anyone except on-duty law enforcement officers from carrying weapons on the campus.