WASHINGTON - At least five bomb threats were reported on Tuesday against flights of five airliners leaving or landing in the United States, US media reported, citing government sources that the threats were not deemed credible.

The five threatened flights include four operated separately by US Airways, Delta Air Lines, United Airlines and the Mexican carrier Volaris, which had landed on the ground, and the Korean Air Flight 23 from Seoul to San Francisco, which was still in the air and was scheduled to land Tuesday afternoon, according to NBC News.

Police and a bomb squad have searched for possible multiple devices aboard US Airways Flight 648, from San Diego to Philadelphia, after it landed Tuesday morning at Philadelphia International Airport.

According to a statement from the airline, there were 93 people on board the plane, namely 88 passengers and five crew members. All people were reunited with their luggage and were free to go, the statement said.

So far, no injuries have been reported. Authorities said there was no indication that the threat was real, the report said.