(Richmond, IN)--Two Richmond firefighters sustained non-life-threatening injuries battling a fire that broke out at a vacant apartment building near 12^th and East Main Sunday night.  "The attic was billowing heavy, dark smoke," said Battalion Chief Eric Holmes in describing what firefighters encountered when they arrived.  The building had four apartment units.  None of them were occupied, but there were squatters known to be inside the building at times.  And, as for the two injured firefighters…"We had one firefighter go to Reid (Health) for difficulty breathing," Holmes said.  That firefighter was admitted.  The other suffered minor burns to the arm.  The cause of the fire remains under investigation.  Crews were on the scene until 2 o’clock Monday morning.