Here is a link to the NY Post story, it has answers to some questions that have been raised here (there was only one chaperone on board and yes the bus is a double-decker) and also a picture of this unfortunate young man and the bus itself.
The bus was travelling from queens to nj for the party. I don’t know why that would be unless it was just that the party was being held in Jersey. It appears this was another over-the-top sweet 16 affair, I can’t imagine what it must cost just to rent that bus!
It’s very tragic, the deceased was a very handsome young man. And judging by what others have said, and heck yes, even my own experiences, he was just miserably unlucky yesterday.