I don't remember it happening but we were shown it at our fire training too.
The marshals had chained the entrances shut to stop people coming in after the game had started, so they all ran down the tunnels to escape and got stuck... by the time the people pushing from the back had realized it was blocked, the fire had trapped loads of people in the tunnel.
The guy leading the fire training was saying that the guy on fire would have actually been dead by that point, his body was just in shock from the nerve damage.
Horrific... all because of a load of rubbish...