According to an airport spokeswoman, someone gave a handwritten note about a bomb aboard Alaska Airlines Flight 342 to a representative at San Francisco International Airport. Officials there contacted authorities.
The plane from Seattle landed safely at about 8 a.m. - about 15 minutes ahead of schedule.
About 150 passengers were evacuated, while bomb-sniffing dogs inspected luggage on the tarmac.
Authorities say no bomb was found on the plane, and the baggage was being rescreened.
The Associated Press contributed to this report.
