( CNN ) -- Federal officials are investigating how firecrackers got into a Southwest Airlines plane scheduled to leave Las Vegas on Tuesday . Southwest Airlines Flight 2408 was leaving Las Vegas McCarran International Airport and was headed to Kansas City , Missouri . The flight was delayed for an hour when a flight attendant found a plastic bag with firecrackers underneath a seat , said Ashley Dillon , an airline spokeswoman . Passengers deplaned . After an inspection that included re-screening luggage , the Transportation Security Administration declared the plane safe and allowed passengers to re-board . It landed safely in Kansas City an hour behind schedule , the spokeswoman said . None of the passengers claimed the plastic bag , but the TSA said it is investigating how the prohibited items got onto the aircraft .
The Southwest Airlines flight was leaving Las Vegas for Kansas City , Missouri . It had a full load of passengers and crew on board when it crashed into the mountains in western New Mexico.