The item was spotted in an X-ray machine by an airport security screener at 10:15 a.m., airport spokeswoman Rosemary Barnes said.
The Alameda County Sheriff's Office bomb squad was called in, and the security checkpoint in Terminal 1 where the item was found was shut down until just past 11:30 a.m.
Barnes said she did not know what the item was.
She did not have information on flight delays, but said that airlines had been kept informed during the incident and she expected they would take steps to accommodate their customers.
