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 Dalla