Newswatcher- This is not a problem! I'll explain as the concept is true of all aircraft and it works a treat - really since Pontius was a Pilate.
Fire Detection Systems and Fire Suppression Systems work outside the engine but within the pod. The analogy with a car is that the two systems are located round the engine, outside of the engine but under the bonnet. The detection system works on excess heat. If the fire is in the engine itself it is safe (after all there is a whole ring of flames in the combustors) but the temperature will rise and eventually set off a warning. If the fire is outside the engine the warning will be activated quicker as that is a bit more serious but the heat gets to the Detection System more quickly as it is closer!
Activating the extiguishers will do two things. Most importantly it cuts off the flow of fuel to the engine thus taking away one side of the Fire Triangle (the other two being Heat and Oxygen). It also floods the engine bay (the space between the pod and the engine) with extinguishant. Again, in the car analogy, it sprays in under the bonnet, not into the cylinders. If you sprayed it into the engine it would simply get blown out the back anyway! Any fire inside the engine will quickly burn out as you have removed the fuel supply and the engine itself will not burn. You may get some oil from bearings buring off as well, again quite safely.
We don't know what happened here but it sounds like it was a fire in the engine itself, not between the pod and the engine. This is probably why there was smoke but no fire warning - yet. Given time, and before any real damage occured outside the engine, temps would have risen in the pod and the Pilots would have instantly swung into action when the Detection System activated. The Fire Service will have simply put out any residual fires in the engine (as they like doing that sort of thing!) and I suspect the the boys in the Cockpit pulled the handle to just make sure there was nothing untoward smouldering in the pod as a sensible precaution.
As you can see, all quite safe and undramatic! Hope this answers your questions.
Regards, H 'n' H <img src="smile.gif" border="0">