He may look old and innocent-looking, but he's a serial bank robber and a wanted criminal in the San Diego area, authorities say.

A man described as being in his 60s or 70s walked into a Bank of America in Rancho Santa Fe, Calif., and presented a note while displaying a gun, the FBI says.

He is suspected of four bank robberies since August, a local television station said Wednesday.

Investigators have released surveillance photos in hopes that someone might recognize the man and alert authorities, San Diego 6 television reported.

The robbery affected a nearby Rancho Santa Fe middle school. "There was a lock down at the school because there was a robbery and there were copters flying everywhere," seventh-grade student Dylan Fetzer said. He said he felt "pretty stupid ... because we were hiding from an old guy with a gun."