Nine first-responders were killed, seven others injured and two were missing as they battled a fire of unknown origin that destroyed an archive of bank documents in Argentina's capital on Wednesday, AP reported.The fire at the Iron Mountain warehouse took hours to control and the sprawling building appeared to be ruined despite the efforts of at least 10 squads of firefighters.The nine firefighters and civil defense workers were crushed when a brick wall collapsed on top of a large group of first-responders on the sidewalk and street outside, Argentina's Security Secretary Sergio Berni said.