Officers said 18-year-old Elijah Pellum was standing around a group of men at Fink White Park in Southwest Fresno.
They said Pellum had a nine-millimeter pistol with live ammunition in his waistband. Several kids playing nearby were moved out of the area.
Pellum was arrested and booked into the Fresno County Jail. He also has a prior arrest for a shooting back in 2015.