The description of the occupants of 2602 seems unreal.  A prior homeless guy living with his friend and girlfriend.  Complaints against them for working on cars in garage. First news reported smell of gasoline in room.  Cleaning auto parts with solvent like liquid in 2602?  These folks aren't the type that I'd feel comfortable with if I was a neighbor.  They should be questioned more and maybe a lawsuit against the parent owners will bring out more details.  Four innocent folks killed is no laughing matter, let alone the property damages to the building.