Try to start earlier than that. We haven't even met this Josh kid yet. Who is he? What is his personality like? Why was he out today? Does he have friends, parents, hobbies? What are his dreams and hopes?
Why should I care about this random person who I don't know, on this random planet I know nothing about, being attacked randomly by some guy who can shoot fire?
Nothing has been established yet, and we're already in the thick of it. Now, that doesn't mean that you have to list all that stuff. You can sprinkle it it throughout the first chapter, all natural like.
But you
must establish, at least, what type of person Josh is before you get to the action, because if you don't the reader has no reason to care about him.
Hey son, wanna' learn how ta' make witch balls?