He's charged with aggravated robbery.
Police say during the robbery, Hernandez pulled out a gun, put it to the clerk's head, and demanded money from the register.
The clerk opened the drawer and was then ordered to lie on the floor.
Hernandez allegedly removed money from the drawer before grabbing the clerk's purse and making off with her wallet as well.
He's being held in the Wichita County Jail bond is set at $100-thousand.