It happened just before 1 am Thursday at the Speedway gas station at Sierra Avenue and Front Street.
The Tulare County Sheriff's Office says three people came in with two rifles.
Deputies say the suspects stole a cash register containing an unknown amount of money and took off in a gray Hyundai sedan.
Investigators processed the store for additional evidence.
If you have any information on this case, you're urged to contact the Tulare County Sheriff's Office.