Kids make this kind of mistake all the time. This is why fireworks should always be supervised with a grownup (25+, mentally mature adult). I once set off a firework horizontally from a balcony of a highrise (my aunt's apartment) once, thinking that it was just some sparkle flares but it turned out to be a rocket, landing into some clotheslines of a neighbor's balcony burning their bedsheet.
I was only 13 at the time.