Surveillance video shows the suspect spraying a store employee with bear spray or pepper spray as she escaped.
The suspect got away in a stolen car.
The car was later found in Collegeville following another robbery attempt. That's where two male juveniles were taken into custody.
Police are still trying to track down the female robbery suspect.
Anyone with information is asked to contact the Upper Merion Police Investigations Division at 610-265-3232 or submit a tip online.