Albert P. Witt, 15, of Belfast pleaded guilty Wednesday to one count of first-degree robbery.
The plea, entered in Allegany County Court before Judge Wayne A. Feeman Jr., satisfied an indictment charging four first-degree robbery counts and one of second-degree burglary.
District Attorney Terrence Parker said Witt is to be sentenced Oct. 26.
Parker said Feeman has granted Witt status as a juvenile offender.
He has been confined in a detention facility in Buffalo since his arrest shortly after the April 20 robbery.
Witt was accused of using a loaded .22-caliber handgun to intimidate the clerk at the Caneadea Gas and Deli store into handing over money, then taking her van as a getaway car. State troopers said Witt crashed the van shortly after taking it, then fled to a nearby house where he was apprehended.