Gauthier allegedly pulled a handgun on a clerk at the business in the 5300 block of Lake Murray Boulevard in La Mesa and demanded cash from the register, according to police.
After the victim handed over an undisclosed amount of money, the bandit left the shop and fled the area to the north in a dark-gray Mazda 6, according to reports.
An officer responding to the robbery spotted the car in the 5000 block of Baltimore Drive, pulled it over and arrested Gauthier. The stolen cash and a pistol were recovered from the sedan, police said.
—City News Service contributed to this report.