( CNN ) -- A Pennsylvania patient accused of shooting his caseworker to death has been charged with first and third-degree murder , authorities said . Richard Plotts was arraigned late Saturday at his hospital bed , said spokeswoman Emily Harris of the Delaware County District Attorney 's office . He is also charged with attempted murder , recklessly endangering another , assault and simple assault , and carrying a firearm without a license , Harris said . On Thursday , Plotts , 49 , walked into the psychiatric unit Mercy Fitzgerald Wellness Center in Darby , Pennsylvania , alongside his caseworker Theresa Hunt , 53 , according to Delaware County District Attorney Jack Whelan . The two went into psychiatrist Dr. Lee Silverman 's office and an argument erupted , Whelan said . Hunt shut the door and called police . Moments later , shots were fired . Another doctor and caseworker ran into the room and found Hunt wounded , authorities said . The physicians wrestled Plotts to the floor and held him until police came . A bullet grazed Silverman 's head . He was treated and released after investigators interviewed him . Silverman used a gun he was carrying to shoot Plotts in the arm and torso , authorities said . Plotts was being treated at the Hospital of the University of Pennsylvania . It 's unclear why Plotts opened fire , authorities said last week . Whelan told CNN affiliate WPVI , `` This could be a much different situation if the perpetrator was allowed to continue with his actions , so I give credit for the staff for intervening . '' Two guns were recovered at the scene -- Plotts ' and Silverman 's . It was n't certain who shot Hunt but , according to Whelan , investigators believe Silverman shot Plotts in self-defense . DA to decide whether to charge killer of intruder who yelled ' I 'm pregnant ' CNN 's Kisa Mlela Santiago , Shelby Lin Erdman , Dominique Dodley , Christy Lenz , Chelsea Carter , Allison Malloy and Rob Frehse contributed to this report .
DA spokeswoman : Richard Plotts is charged with first and third degree murder , among other charges . Psychiatrist uses gun he was carrying to shoot suspect , authorities said . A caseworker was killed and two people , including suspect , were wounded in the shooting .