My assumptions:
-I don't know the kids
-I don't live in an apartment so it's not my home but I'll assume it's in my area
-I don't have time to get to my truck which has a fire mask and fire extinguisher in it because I'm a paranoid prepper
-I'm on a floor too high to throw them out the window
Since it's my neighborhood I'd check (quick glance) if it was in fact a meth lab and about to blow up, in which case I'd deuce with the one kid. Not a meth lab and no mask? Deuce, smoke inhalation is what will be my downfall not the fire, can't help if I'm not awake. If I had my mask I'd risk it, it's my neighborhood so that apartment is going to be well under 1000 SqFt and a quick clear. If there was a lot of debris because it's my neighborhood and that 1000 SqFt was cluttered af I'd deuce even with the mask. So I guess the answer to the question is I'd do as much as I safely could. Like others have said I'm not a hero, I'll help but I'm not dying for strangers, kid or not.
Thanks for asking this though I think I'll invest in a fire blanket too for the truck.