RIP to those involved. Horrible way to go.
The most worrying thing in my mind is that the plane crashed on its second takeoff attempt. An earlier takeoff attempt was aborted due to technical issues. Of course the two things might not be at all related but I imagine a lot of questions are going to be asked regarding the aborted takeoff.
I watched a few bits about this on the news earlier and it was said that it is a legal requirement that a plane such as this is able to sustain flight with a single engine failure. Engine failure at takeoff is probably one of the worst times for it to happen but I would think that something other than engine fire/failure must be the cause here, or, to be more exact, subsequent damage caused by the engine failure (there were reports of an explosion prior to the crash itself) brought the plane down rather than engine failure itself. I'm no expert and this is pure conjecture.
Anyway, i don't particularly wish to get into a discussion about such a sad event. Just a few things I felt like saying.
Once again, rest in peace.