Some kid had his foot blown off in an explosion in Central Park this morning and the cops are saying he may have "stepped on a discarded firework" while climbing rocks. But that sounds a little iffy to me. I've never heard of a firework exploding when someone stood on it, I thought they had to be lit. Unless of course he created a spark somehow? Perhaps he had a tack in his shoe which sparked when he was climbing the rock, I don't know. But it sounds to me like the kids were looking to set off their own fireworks and disaster struck, now they're denying all knowledge. Time will tell. 
 
That a firework can blow your foot off I can believe. The hoodlum kids in my neighborhood always somehow manage to get hold of a huge stash of those illegal fireworks which literally sound like bombs going off, and the whole month surrounding July 4th sounds like a war zone with long series of very loud bangs sometimes going on all night, and I often think it's only a matter of time before one of them loses a limb. 

Is this possible?  Technically, yes.  Because the pressure of the foot on the firework could have caused friction.  But I'd be more likely to lean towards the kid lighting the firework then trying to step on it to put it out because someone was coming.

The low spark of high heeled boys, according to steve winwood...

We used to crack open dud firecrackers, light them and throw 'em and stomp 'em to make 'em go bang

It depends on what the explosive is.
 
I remember these things as a kid, which were designed to to pop when pressure is applied:
 
https://en.wikipedia.org/wiki/Bang_snaps
 
 
It's also possible it was just a delayed fuse set by some idiot.

Now they are reporting it as a homemade bomb...
 
"A college student stepped on a “homemade” bomb in Central Park Sunday, blowing off his left foot, authorities said."
 

Sounds like they'll accept just anyone into college now-a-days, eh? 

I really don't know but I guess it would be feasible. If any remembers the old red perforated tape for cap guns, it would 'fire' from being struck. We would pop the entire roll with a hammer. Maybe if someone jumped/stomped on that firework hard enough...

If you wrap a bundle of old fashioned 'sparklers' real tight with duct tape ...

Here's a strange one for you:
Phantom Fireworks and other more "fly-by-night" dealers exist in the corner of Pennsylvania where I80 enters the state from NJ. It is illegal to buy or set off fireworks in PA, meaning that Phantom must sell entirely to out-of-state customers. So, Phantom sells to anyone from any other state regardless of the legality of fireworks in that person's state, as long as one can prove that he is not from PA. Obviously, with I80 having the fastest access, NJ customers make up a huge percentage of Phantom's customers. PA authorities are not concerned with any reciprocity on this issue. At this time of year, NJ State Police do stop drivers coming from PA to check for fireworks. I'm not sure if a policeman or other individual is stationed outside Phantom and calling in the NJ license plates of customers for checking, but I heard that was the case at one point.
 
I have a friend I played with who is a drummer for Rob Zombie and Alice Cooper. He has a very cool annual 4th of July picnic on his lake island in northern NJ. The police are always invited and they bring the contraband firework with them to be set off at the picnic legally.