However, the FBI later determined that the telephoned threat wasn't credible.
"There was no fear in the cabin at all," passenger Michael Kidd said. "It was pretty calm. Even with the frustration of having to sit there, there were no raised voices."
Police eventually entered through the back door and arrested the two passengers. Others on board were taken off the plane six at a time and put on a buses. San Francisco Police Department officers used security wands to screened them and their carry-on luggage.
"The two passengers were taken off the plane separately, but we cannot discuss the specifics why," said FBI spokesman Joseph Schadler.
Police were investigating who called in the hijacking threat and what their motivation might have been.
The Flight was already running 2 1/2 hours late when it pulled away from the gate at 10 am local time. Minutes later, it was being dispatched to a remote stretch of tarmac at San Francisco International Airport where it sat for two hours.
Passengers were taken by buses to a terminal for further security checks.