Oh man if the construction company that nobody wanted down there ended up causing the explosion, the lawsuits will be Crown Center walkway-esque 
Crown Center was a design flaw on the engineers end. The plans they drew up showed the walkway couldn't withstand the weight and they ignored it or didn't see it, that's why they got sued. Someone gave their word as a professional that the design was good to go and it wasn't.
Unless there was a flaw with the gas company's installation of the gas line and a car crash caused the leak, I don't think it even matters if they called or not, they won't be held liable. If it was leaking before hand that's another story. As far as I know, utility companies are not responsible for anything besides "wear and tear" especially if damage happens that quickly.
Yeah, it reminds you of Crown Center because they are both tragedies in Kansas City. One was a series of dumbasses being lazy, this sounds like a straight up accident.
On another note, how'd you like to be the person who crashed your car into the building and made it go boom? T's and P's for everyone.