Both people on board the jet were killed.
A fire official says controllers told the pilot of the jet to take off quickly because a Southwest 737 with some sort of problem was approaching.
District chief Tommy Dowdy says the Cessna Citation 500 took off — but then it encountered a problem. Dowdy says the pilot asked if the jet could return.
He says it crashed on one of the runways, caught fire and slid across a grassy area to a parallel runway.
Officials don't know what was wrong with the jet.
Meanwhile, the Southwest Airlines plane was diverted to the city's other major airport. It landed safely.