Police say witnesses called them to the scene on Shaw and Marks just before 11 a.m.
They say the masked men entered the Check-N-Go store, demanded money from the cashier and then sprayed her with a chemical believed to be pepper spray.
"One of the clerks at the Check-N-Go was sprayed with a caustic chemical we believe that to be pepper spray. She's been treated by EMS staff. Her injuries are extremely minor. She's experiencing some discomfort and that's about it," Lt. Burke Farrah of the Fresno Police Department said.
Witnesses told police the suspects got away in a gray Volvo. They tracked down the vehicle and arrested one of the suspects.
There's no word yet on how much cash was taken. Police believe this crime is related to two other robbery attempts at check cashing establishments in Northwest Fresno on Thursday.