The man, dubbed the "Quad Bandit," used an envelope or just a note demanding cash from tellers at four banks, FBI Special Agent Chris Gicking said.
He reportedly bounced from bank to bank on March 22 until a teller at the fourth branch finally complied with his demands. The robbery attempts occurred within 30 to 45 minutes of one another, splitting up police resources.
"I have never seen a robber at least attempt robbing four banks in one day," Gicking said. "That would be a first."
The man apparently hasn't tried to rob any other banks since that day, Gicking added.
The Quad Bandit is described as a white male who wore a white crew-neck shirt, jeans, sunglasses and a tan Los Angeles Dodgers baseball cap.
The announcement comes as investigators say they arrested two other bank robbers linked to at least five robberies in or near Orange County.
Albert Jamel Limbrick, 25, of Long Beach and Paul Sayer Kjelland, 36, of Garden Grove were taken into custody Friday on suspicion of the robberies, according to an FBI statement.
Kjelland allegedly robbed banks in La Habra, Aliso Viejo and Huntington Beach. He also allegedly tried robbing a bank in Orange and is suspected of holding up a bank in Lakewood, according to the FBI.
Limbrick is accused of robbing a Farmers and Merchants bank in Laguna Hills on March 20, according to the FBI.