Although I doubt anyone EDCs a hammer...
I believe that the fire started in the freight section, where heavy trucks are ferried under the Channel. I think it's logical to assume that the truck drivers had tools in their vehicles that they grabbed to smash the window(s).
I was just reading another update on this fire. There have been a few tunnel fires since the Eurotunnel service started, and all of seem to have originated with trucks catching fire. I wonder if the owners of these trucks are ever held responsible for these fires that started with their vehicles?
At first, I was thinking about how frightening it seems being stuck under the Channel during a fire. But, on second thought, it's not quite as scary as I thought when I remembered that you're always going to be on a train with trained personnel who have presumably been drilled on what to do, there are onboard safety systems, and you are hopefully only a short distance away from safety in the adjacent service tunnel. That's a far different situation than, say, the Mont Blanc tunnel fire where everyone is driving their own vehicle deep inside some tunnel. In that case, it's every person for themselves and if you don't know what to do or where to flee to safety, you're out of luck.