Denzel Bates, 17, an employee of the restaurant, was arrested Friday at his home, according to an e-mail from Cpl. 1st Class Jeremy Hembree.
Hembree said Bates participated in planning the robbery and was on duty the night it happened.
Investigators are searching for Marquis Carter, 26, of New Ellenton in connection with the same robbery. Hembree said Carter is considered armed and dangerous.
Police are also searching for a third unidentified male.
Investigators are asking that anyone with information related to the whereabouts of Carter or the identity of the third individual call Crimestoppers of the Midlands at (888) CRIME-SC. Callers will remain anonymous and could receive a cash reward of up to $1,000.