A senior law enforcement official told NBC 4 New York that preliminary information suggests that the explosion was a firework accident that led to a significant foot injury, possibly an amputation.
The official also said friends of injured man deny they were playing with fireworks, so the NYPD bomb squad is investigating to determine what the material is that caused the injury.
Pictures a little graphic - http://www.nydailynews.com/new-york/blast-elie-wiesel-funeral-central-park-severs-man-leg-article-1.2697682