No money has been recovered, Potter said.
Shelton already had been charged in the Jan. 22 armed carjacking of a taxi cab that was used in the robbery of the bank.
Shelton, who gave police an address in the 600 block of West Washington Street, was arrested Saturday night on those earlier charges.
Bond had been set at $500,000 for the carjacking offenses, but bond was denied Monday on the bank robbery/assault charges.
Police said a man armed with a silver handgun forced the driver and three passengers from a Turner's taxi cab on Jan. 22 at the rear of 1016 Linwood Drive at about 9:48 a.m.
The cab was used in the 10 a.m. robbery of the bank at 16802 Virginia Ave., police said.
Shelton earlier was charged with armed carjacking, armed robbery, robbery, theft, four counts of second-degree assault, carrying a concealed deadly weapon and use of a handgun in the commission of a felony, police said.
Hours after the bank robbery, the Maryland State Police found the cab at the intersection of Duke Drive and Pickett Court in Williamsport. A red dye pack had exploded in the cab.
Police initially thought the robber had another vehicle waiting where he ditched the cab, but Potter said the robber was allegedly hiding at the nearby house of a girlfriend.
There were no injuries in either the carjacking or the bank robbery.
The Hagerstown City Police, state police and FBI are cooperating in the investigation of the crimes.