Two of the suspects were caught on camera.
The robbery happened around 4:15 a.m. on Monday at the Sunoco station at 406 Mantua Avenue on Route 45 in Woodbury.
One man had a shotgun and pointed it at the clerk, police said, then punched the clerk while he was on his knees.
The group stole about $600 in cash then fled the store on foot.
Anyone with information is asked to contact Woodbury Police at 856-845-0064.