A woman called police sometime around 1 a.m. after she believed she saw two people carrying guns enter the store on Sharon Park Drive, police said.
Police arrived within minutes and surrounded the building, then evacuated the store.
An extensive search failed to turn up any gunmen, and police said the woman was simply mistaken in what she saw.
Police, however, still encourage residents who think they are witnessing a crime in progress to contact them immediately.
The Palo Alto Police Department and the San Mateo County Sheriff's Office assisted in the response.