Hydrogen cyanide and explosions

I'm completely in the dark here, I'm afraid. I made the assumption that hydrogen cyanide (lethal gas, like they use in executions) is combustible, first of all. I tried googling it, and I'm fairly certain that I'm in the clear there, but if someone could confirm this for me, that would be great.

Now, my main question is how would such an explosion work? I can find news stories about natural gas explosions, and essays about hydrogen bombs, and I don't remember what all keywords I've used. This takes place in a mysterious, abandoned airport in the middle of nowhere. There is power, and the kitchen in the restaurant has an open-fire stove.

Please don't ask why there's hydrogen cyanide. He's part of the cast.

What happens when the gas hits the fire? Immediate explosion seems more like something that would happen in an action movie with Steven Seagal. I'm thinking the gas would act as a kind of wick rather than actually explode, but I'm hoping I'm wrong. As a backup plan, I thought about having the gas be in the oven, and then the heat makes it explode, but I'm not entirely sure how sound that is, either.

Thanks in advance.

EDIT: Crap! Thanks to lt260 for reminding me. Would the sprinklers coming on kill the fire, or make it worse?