Prayers up for them. Horrible.
Looks like the spark made the gas bottles let go all at once.
Hopefully it was over quickly.
Yep... would guess it was a propane issue. Horrible... that means the passengers were probably being burned to death as the balloon was crashing.
A power line strike at basket level is about the worst thing that can happen to a balloon. The momentum of the balloon pushes the cables against the side of the basket, and then pushes the cables together. That results in a huge arc right at the outside of the basket, inches from the propane tanks. Often, as probably occurred in this disaster, the arc cuts through the tanks, resulting in an immediate, uncontrollable fire.
That is why balloon pilots are trained to avoid power lines, and if one is approaching, perform an emergency deflation to drop under it.
Prayers for those aboard the flight, and their families and friends.