Airline officials said law enforcement officials determined the threats Tuesday did not exist after passengers and luggage aboard the two flights were rescreened, The (Phoenix) Arizona Republic reported.
When it arrived at Phoenix's Sky Harbor International Airport from John Wayne Airport in Orange County, Calif., Flight 1184 was taken to an isolation area where all passengers and luggage were rescreened, Southwest Airlines spokeswoman Ashley Dillon said.
Flight 811 was also scheduled to depart Orange County for Phoenix but was stopped in California for similar reasons, Dillon said.
Laura Eimiller, a spokeswoman with the FBI office in Los Angeles, said officials removed passengers while a bomb squad and canine units searched the plane, CNN said.
"No threats of any kind" were found, said Lt. Joe Balicki of the Orange County Sheriff's Office.
A third plane from John Wayne Airport to Phoenix arrived without incident, Dillon said.