The same woman is believed to be responsible for three bank jobs on Monday morning.
The first heist took place at a Wells Fargo in the 5600 block of Mission Center Road in Mission Valley around 9:45 a.m.
An hour later, a Mission Federal Credit Union was robbed in the 3800 block of Avocado Boulevard in El Cajon.
Fifteen minutes later, a woman matching the description circulated after the first two robberies struck a Chase Bank in the 3400 block of College Avenue. Investigators said that in all three incidents, the woman showed a demand note that said she had a gun.
The robber got away with cash in the first two robberies but fled before getting a dime in the Chase Bank incident, despite the fact that the clerk was in the process of complying with the demand when the woman left.
"Her cellphone rang, she (suspect) answered her cellphone and turned and walked from the bank,"said San Diego Police Lt. Todd Jarvis.
According to police, officers are searching for a heavyset woman in her 20s or 30s. She may have fled in a white four door nissan sedan.