SAN FRANCISCO, Jan. 2 (Xinhua) -- U.S. Alaska Airlines Flight 915 was forced to be canceled Tuesday after a rat was spotted jumping into the aircraft, its passengers said on their Twitter accounts.

Flight 915, which was scheduled for departure from Oakland, California state, to Portland, Washington state, on the west coast of the U.S. Pacific, was canceled after passengers boarded the plane.

Most of the airline's 110 passengers were directed to another flight to Portland later Tuesday.

"Our flight to Portland is delayed because when they opened the door on arrival a rat jumped into the plane. There are 4 people trying to locate it," a passenger named Matt Gough tweeted.

Another passenger also said on his twitter account: "AlaskaAir flight got canceled in Oakland due to rat on plane."

Alaska Airlines said in a statement that the plane "is currently out of service."

"It will be returned to operations once it's certified rodent-free by a professional exterminator. The aircraft will also be thoroughly inspected to ensure no damage has been done," said the U.S. airline.

As a major U.S. air carrier founded in 1932 and headquartered in Seattle, Washington state, Alaska Airlines has flights to more than 100 destinations in the United States and beyond.