Sounds like it from the drone of some giant military helicopters sweeping across the skies today. Robin Blackman shot the video above as a trio of choppers swooped over Elysian Heights while Jeanne Wyshak snapped some photos (below) as they made a pass near Dodger Stadium. What’s going on? The choppers have apparently been flying across Los Angeles, attracting attention and generating commentary and speculation on Twitter. There’s talk it could be in connection with President Obama’s upcoming trip to Southern California.