The robbers took a backpack containing between $300,000 - $400,000 worth of jewelry from two couriers, who had just driven from a store on Montana Avenue at about 4 p.m. on Tuesday.
Santa Monica police say one of the robbers was carrying a gun, and that they may have had an accomplice at the wheel of their getaway car.
Authorities said the robbers appeared to be in their 20s and 30s. One suspect was described as a Hispanic man between 5 feet 9 inches and 5 feet 11 inches tall with black hair, wearing a maroon hooded sweatshirt and a bandana around his face. The second suspect was described as a black male with a medium build, also wearing a hooded sweatshirt and a bandana around his face.
They took off in a dark colored compact vehicle.