Doubt heavy equipment involved, more'n likely a "reno" job. (read; day laborers)
Well, Bloomberg did say NYC couldn't function without them.
Out here in the sticks, the usual suspect in construction is the backhoe on buried lines. "Call before you dig."
I could see how in an urban environment it would be more likely for somebody to knock loose or crack a gas line up in a building.
With the ConEd report of a strong smell of gas, seems likely that somebody knocked a cap off or crimped a pipe.