Authorities at San Jose International Airport searched an Alaska Airlines flight Sunday after a flight attendant found a note that read: “Bomb on board.”

The flight attendant discovered the note on a food tray during the flight and immediately notified airport authorities, the Federal Aviation Administration said.

All 128 passengers and 12 crew members aboard Flight 482 that originated in Spokane and made a stopover in Portland were ushered safely off the plane after it landed at San Jose and held briefly in a secure area while their luggage and the plane was searched, the FAA said.

“We had no choice but to take it seriously,” said San Jose Police Lt. Dennis Luca. “I don’t think with what’s happened in the past seven to eight days, we could not take it seriously.”

A bomb squad aided by dogs and the police department searched the plane but did not find any explosive device, said Alaska Airlines spokesman Lou Cancelmi.

The incident forced airport officials to shut the airport for about 30 minutes. It was reopened at about 3 p.m.