Oakland International Airport spokesman Brian Kidd says the flight landed without incident at 9:10 a.m. Wednesday. No one was injured.
Another airport official, Kim Domerofski, told the Oakland Tribune the crew had reported a possible bird strike and decided to land as a precaution.
The newspaper reported there were 166 people on board.
Alaska Airlines spokeswoman Marianne Lindsey told the Tribune an examination of the plane showed something was ingested in an engine, although officials didn't know what it was.
The passengers and crew were transferred to another plane that left for Hawaii at 10 a.m.