The first robbery occurred at 1:50 a.m. in the 12500 block of Ventura Boulevard, and the second robbery occurred about four hours later in the 3700 block of Cahuenga Boulevard.
In both cases, the man showed the employee a gun and then demanded money and cigarettes.
Authorities say the suspect is between 30 and 40 years old, about 5 feet 11 inches tall, 200 pounds and possibly has a lazy left eye.
The suspect was driving a red, four-door, 2015 Chevrolet Cruze with a sunroof and unknown license plate. The suspect should be considered armed and dangerous, police said.
Anyone with information on this case was asked to contact the Los Angeles Police Department's North Hollywood Division at (818) 754-8424 or (818) 754-8426.