Officers went to the mobile phone service store in the 600 block of Contra Costa Boulevard at about 7:30 p.m., according to Pleasant Hill police.
Two men wearing masks and all black clothing had entered the store carrying handguns and demanded money from the store clerk, police said. Two customers in the store were held at gunpoint and one of their wallets was stolen, police said.
Money was taken from the cash register and the two robbers fled the area on foot.
No one was injured.
The two suspects were described as black men in their mid-20s, police said.
Anyone with information regarding the robbery is asked to contact Pleasant Hill police investigations at (925) 288-4630.