Brea and Santa Ana police are investigating three other 7-Eleven robberies in those cities, including two that happened Thursday morning in Santa Ana to see if they involve the same suspects.
Police believe since June 20, the same suspects have pulled off at least 13 robberies in nearly a dozen cities across L.A. and Orange counties, including Lynwood, Long Beach and Carson.
Investigators are looking for two suspects, ages 18 to 25, who are about 5'4" to 5'9". They usually wear dark clothing and hooded sweatshirts. In some instances they have had a goatee or mustache.
"The robberies primarily take place in the very early morning hours ... sometime from about midnight to two or three in the morning," said Sergeant Rick Martinez, Anaheim Police Department.
In one incident in Placentia, the suspects left with cigarettes when the clerk refused to open the register. However, police say they're concerned because the suspects appear to be getting more violent. In San Clemente, the suspect cut the clerks hand, even after the clerk had opened the register.
"Probably indicates either a drug habit, or a gambling habit ... because, again, that's a lot of robberies in a short period of time," said Jim Amormino, Orange County Sheriff's Department.
In many cases, the suspects have left with less than $100 in cash.
Anyone with information is urged to contact the Anaheim Police Department at (714) 765-1959.
City News Service contributed to this story.