Sorry to drag this back to the evacuation, but WTF.
Very few things in aviation should be rushed and the decision to evacuation is a case in point.
On the 737 checklist items include the engines being switched off, the speedbrakes being stowed and the flaps set to 40 in order to aid the evacuation. Initiating an evacuation before these steps have been taken are likely to cause injury or death.
If passengers initiate an evacuation they are doing it with very little information, very little situational awareness and most likely whilst in shock with adrenalin pumping. Once an evacuation has started it cannot be stopped, people will get injured.
The rear slide angle and the wing at flap 30 with an unusual nose attitude must have injured people during the evac.
Only a few weeks ago in the Asiana incident someone was run over and killed by a fire vehicle in broad daylight further demonstrating that the aircraft can often be the safest place to be.
If there's a fire or smoke in the cabin, I would agree get the hell out of there and if the pilots didn't know what the situation was they'd soon switch the engines off when the doors are flung open, but a few sparks outside as the aircraft slows to a halt, get grip of yourself and let those with all the information make the decision.