Whatever happened, it was so fast that there was no time to do anything. I do not believe for a second it was a lightning since this plane is one of the modern ones that can handle that and more! They even have a system that the plane could have returned to Brazil easily so whatever was the cause, it was either an explosion inside the plane or a combination of things. A tragedy.
maybe they were shot down by some new weapon that someone is keeping a secret. Or they ran into a UFO that was hiding in the storm. I can think of a lot of scenarios but most of them would give time for a distress call. Hearing nothing means something major happened and I hope they get it figured out.