Investigators believe Ronald Glenn Jones, 54, walked into the Bank of America at 2178 Contra Costa Blvd. shortly after noon, approached a teller window with a silver pistol, and presented a note demanding cash, police said.
The suspect then fled with the money.
Police have not said how they identified Jones, but according to initial reports from police on Saturday, the suspect had been seen wearing a full-length yellow raincoat and had a large piece of white gauze taped to his right cheek.
A no-bail warrant has been issued for Jones' arrest, and police said he is believed to be armed and dangerous.
Police said Jones' last known address is in Oakland.
Anyone with information regarding his whereabouts is asked to call Pleasant Hill police at (925) 288-4630.