A plane at LaGuardia Airport was searched Thursday after someone reported finding a bomb threat against the plane on the Internet, officials said. American Airlines Flight 382 from Chicago landed safely and 117 passengers and five crew members were taken off the plane before the search began. The plane was moved away from other aircraft for the search, but the airport remained open. Bomb-sniffing dogs were sweeping luggage and the plane, and luggage was being matched to the passengers.