Two historic military aircraft collided and crashed Saturday during an air show in Dallas, exploding into a ball of flames and sending black smoke billowing into the sky. It was not clear how many people were on board.

Emergency crews raced to the crash scene at the Dallas Executive Airport, about 10 miles (16 kilometers) from the city’s downtown. News footage from the scene showed crumpled wreckage of the planes in a grassy area inside the airport perimeter. Dallas Fire-Rescue told The Dallas Morning News that there were no reported injuries among people on the ground.