A man walked into the Wells Fargo branch at 1298 E. 14th St. at 10:15 a.m. and began talking to a teller there, police said.
He said several times, "This is a bank robbery," and the teller attempted to alert a manager, according to police.
The man then fled the bank without taking any money, police said. Witnesses followed the man and noticed a San Leandro police car passing by. The witnesses flagged down the officer and notified him of the robbery attempt.
Police searched the area where the would-be robber was last seen and found a man matching his description in the 1400 block of Washington Avenue.
Witnesses told police that the man, later identified as 55-year-old Oakland resident Tony McIntosh, was the same person who had tried to rob the bank.
Police said that while searching McIntosh they found a small amount of crack cocaine on him. He was arrested on suspicion of attempted bank robbery and drug possession.