then the door flung open away from him and he got a split-second glimpse of a flashlight taped to a shotgun barrel , and then the shotgun fired instantly , at point-blank range and a downward angle , right under his bent knees , and the stairwell was instantly full of deafening noise and flame and smoke and dust and wood splinters from the stairs and shards of plastic from where the muzzle blast blew the protruding flashlight apart .