That's the key question.  Did Smith KNOW for certain where his fellow officers were?  How could he know their exact location?  This wasn't like firing at someone thru a wood picket fence, where you can sort of see thru the slats to figure out who or what's on the other side.  These are floorboards in a house, tight up against each other -- possibly with linoleum or carpeting on top of the boards.  It seems unlikely that he'd even be able to see a muzzle flash from where he was inside the house.  He probably just fired repeatedly (10 rounds according to the article) in the general vicinity of whatever hole was made by the suspect's gunshot up into the house.  He made an assumption that the suspect hadn't moved, and was still in the same spot.  But it could have just as easily been an officer down there trying to close in on the suspect.  The point is: Smith couldn't be sure.  He was guessing.  And that could have ended very badly.