The pair were standing in the back of a van at the airstrip and did not see the plane coming in time, causing immediately fatal injuries. They had been at a horse race on Saturday afternoon before heading to the airstrip.
Some witnesses had asked the teens to get out of the vehicle because it was dangerous, they said, but the girls reportedly ignored the warnings.
A spokesman for the state prosecutor’s office said that authorities were investigating the case.
There was no comment from the girls’ families.
The identity of the pilot was not released, and it was not clear how the plane came to be so close to a vehicle on landing.