I cannot express how grieved I am for the people who lost their lives or are injured physically or mentally by this accident. Their is nothing in the world that can compensate for loss of life !
May Allah have mercy on their souls.
In my humble opinion, its no ones fault. The event managers, did their best to keep the crowd away from the strip. However, its not a solution as is evident from this accident. In US the drag strips have a wall barrier on it's sides or at least a metal divider/fence to keep the crowd away and safe from horrible crashes. Bottom line is,
The infrastructure to hold such events is just not there, and its a bad idea to hold quarter miles on open roads and air strips, no matter how big or small the event is.