The suspects wore hooded sweatshirts and covered their faces with masks and bandanas when they robbed the store around 8:45 p.m.
Police say the men got away with up to an estimated $10,000; it was earlier believed the amount was $16,000. They also took cash from a female shopper who was accompanied by a child. Police said the men escaped in a dark-colored SUV or truck that was last seen going southbound on Montebello Boulevard.
Police believe the suspects are black and Hispanic males between 17 and 21 years old. The suspects also appeared to know what they were doing.
"It is possible they were in there for a very short period of time, it could have been planned, they could have done it before, so that is possible," said Montebello Police Lt. Mike Flores.
Police will review surveillance video to try to gather more information. They are also asking anyone with information on the suspects to call the Montebello Police Department at (323) 887-1262.