The first suspect is dubbed the "Valley Bandit" and is suspected of robbing five banks in the San Fernando Valley.
According to police, the suspect usually holds a gun near his waistband and threatens employees and customers.
Witnesses have described him as a Hispanic or Middle Eastern man between 25 and 35 years old, standing between 5 feet 9 inches tall, and weight between 180 and 200 pounds. The suspect was last seen wearing a baseball hat in bank surveillance photos.
The second serial robber is known as the "Foothills Bandit" and is linked to three robberies.
According to detectives, the suspect usually enters the bank and displays a device with various wires, tubes, and blinking lights. The suspect states it's a bomb and demands cash.
He has been described as a white male between 23 and 30 years old, standing around 5 feet 7 inches tall, and weighing about 150 pounds.
Anyone with any information on either suspect was urged to contact their nearest FBI office or dial 911.