The FBI sought the public's help Tuesday in identifying a bank robber who wore a crash helmet during a heist at an Alpine bank and then escaped on a bicycle.

The robber, described as 17 to 25 years old, entered the California Bank and Trust in eastern San Diego County on Monday and yelled, "Give me your money!" the FBI said.

He lifted his shirt as if to show a gun, but no weapon was seen.

When the teller did not move fast enough, he slammed his fist on the counter and grabbed money from the drawer. He fled on a red BMX-type bicycle and was last seen westbound on Arnold Way in Alpine.

He wore a full-face crash helmet and a bandanna or goggles to cover his face. Anyone with information is asked to call the FBI at (858) 565-1255.

-- Tony Perry in San Diego

Photo: Surveillance camera catches bank robber in the act. Credit: FBI