Houston (AFP) – Two World-War-II-era airplanes collided Saturday at an air show in Dallas, US authorities said, with social media footage showing the aircraft crashing into each other and hitting the ground with a fiery explosion. It was not immediately clear how many people were in the two craft, a Boeing B-17 Flying Fortress and a smaller Bell P-63 Kingcobra, the Federal Aviation Administration said. Nor was it clear whether anyone survived the early afternoon crash, which occurred during the Wings Over Dallas Airshow at Dallas Executive Airport. While the number of casualties was not immed…