U.S. Flights Face Bomb Threats, no Explosives Found: Media Reports

According to an airline official and media reports, bomb threat against a U.S. Airways flight from San Diego to Philadelphia on Tuesday led authorities to search the plane and evacuate passengers, but no explosives were found.
Victoria Lupica, a spokeswoman for U.S. Airways' parent company, American Airlines said police met U.S. Airways flight 648, with 88 passengers and five crew on board, when it landed at Philadelphia International Airport due to a "possible security threat,"
Philadelphia's 6ABC television reported a possible bomb threat prompted the search.
NBC and CNN reported that other U.S. commercial flights received bomb threats on Tuesday: a United Airlines flight to Chicago and Delta Air Lines flight to Atlanta. The planes landed safely and were searched, and passengers were deplaned, CNN reported.
The Transportation Security Administration and Federal Aviation Administration referred queries to the Federal Bureau of Investigation, but.
Officials with the FBI were not immediately available for comment.