On Monday and Thursday evenings, a man stole undisclosed amounts of cash from the Lingerie Etc. adult bookstore at 2298 Monument Blvd., Pleasant Hill police Lt. Dan Connelly said.
It's unclear whether the same person committed both crimes, but police are investigating that possibility, according to Connelly.
In both cases, a man with a gun walked into the store and demanded cash from the clerk working behind the register.
He was given an undisclosed amount of money before running away in an unknown direction, Connelly said.
The robberies happened at about 7 p.m. Monday and 6 p.m. Thursday.
Connelly said the store was not too busy when it was robbed Thursday, but police were able to interview a few witnesses.
The suspect was described as a man in his early 20s who is 5 feet 8 inches tall with a slim build.