[user104658]

I think the most likely scenario is that they were lighting fires for "fun" and at some point he's spilled some on his clothes which have then caught a spark. People don't realise just how flammable petrol is - its not just a flammable liquid, just the fumes can ignite if you get too close to source, it doesn't even have to touch the liquid.

It's a tragic story. However - I disagree that a 7 year old should necessarily need to have adult supervision at all times playing outdoors near to their own home. It's stifling, restrictive, and causes more problems in the long run - and incidents (accidents or deliberate harm) are incredibly rare. Children need a little bit of freedom, it's being constantly taken away and as a result we're ending up with several generations of completely incompetent "adults".

Those kids obviously didn't understand the danger they were in. That's where the real problem lies.