Harris allegedly became angry when he realized how little money there was in the till, and fired his gun into the floor during the holdup.
A piece of the bullet deflected into the eye of a Wawa employee, but the worker was not seriously injured, police said.
Smith said King served as lookout man Feb. 9. His photo was captured by a surveillance video camera, and a witness also picked his image out of a photo lineup, Smith said.
King was taken into custody at a home in Philadelphia with the assistance of the Philadelphia Police Warrants Unit and State Constable Michael Connor.
King waived extradition back to Radnor Township. He confessed to his role in the Wawa robbery, Smith said.
King was arraigned before District Judge David H. Lang. He was being held at the Delaware County prison when he could not make 10 percent of his $250,000 bail.
Contact staff writer Bonnie L. Cook at bcook@phillynews.com.