First shot fired from roof, hits Trumps ear, strikes the grandstand, and fragments rupture hydraulic hose.

Second shot from open window on two story building (which is why its outside the security zone) next to roof top shooter, bullet captured in flight, goes on to hit guy in stand.

The last shot was a negligent discharge, from one of the DEI hires, and this is what killed the fire chief.

The second rifle was fired automatically when the first shot was fired, and this also trigger the camera shutters.

If a reaction produces light, and heat, both forms of electromagnetic radiation, then it will also produce radio waves that can be detected.