Well, the backblast from any rocket style weapon in an enclosed space is nasty to be caught in. Training manuals warn against it, "keep #### amount of square footage of open space to allow gases and pressure to exit" etc, etc. I think what toasted your guys was the second floor aspect - they have to go down first, then out. If it was a large building, you were in effect on the 3rd or 4th floor - long way down.