Officials say deputies pulled over Andrew Sharkey in front of Del Mar Elementary School near Ashlan and Del Mar Avenues around 1:30 am on Thursday.
Investigators found a loaded gun in his waistband and then decided to search his car.
Deputies found a gram of cocaine, 100 Xanax pills, marijuana, and drug bags. They also discovered $300 in cash believed to have come from illegally selling drugs.
Sharkey was arrested and booked into the Fresno County Jail on several charges, including having an unregistered loaded firearm in public near a school and drug possession.