A Federal Aviation Administration spokesman said a flight instructor and student were doing some kind of training exercise in a Bellanca Citabria aircraft when the plane went down at the airport at about 3:11 p.m.
Both people were transported from the scene with serious injuries, the FAA said.
The airport is halfway between Midlothian and Waxahachie along state Highway 287.
The FAA and National Transportation Safety Board will investigate what led to the crash.
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