Citizens Energy workers continue their investigation Monday afternoon Nov. 12, 2012 by digging into the front sidewalk looking for possible explanation into the explosion of a house in Indianapolis. The search for what caused a massive, deadly explosion that rocked an Indianapolis neighborhood turned to natural gas Monday, with officials checking gas lines and a homeowner saying a problem furnace could be to blame. (AP Photo/WTHR Chopper 13/The Indianapolis Star, Matt Kryger) NO SALES
