HOUSTON -- A small jet crashed Saturday at one of the city's airports after being instructed to take off quickly because of an incoming airliner. Both people on the jet were killed.

The Cessna Citation 500 was preparing to leave Hobby Airport when controllers told its pilot to take off quickly because a Southwest Airlines 737 with some sort of problem was approaching, said Tommy Dowdy, district chief for the Houston Fire Department.

The Southwest plane, with 119 passengers, was diverted to the city's other major airport, Bush Intercontinental, where it landed safely. Southwest spokeswoman Ginger Hardage said Flight 422 had departed Hobby for Las Vegas but was forced to return to Houston after a cockpit gauge reported a high oil temperature.

After takeoff, the Citation apparently began experiencing some sort of problem and asked if it could return to Hobby, Dowdy said.

Officials did not immediately know what type of problem the small plane had that forced its return.

The jet crashed on one of the runways, caught fire and slid across a grassy area to a parallel runway, Dowdy said.

Neither the victims' names nor their destination were immediately known, Dowdy said.