The cause is still unknown, but fire officials confirm an unknown crew had been working near a home in Fitchburg just days before it exploded. Fitchburg Fire Chief Joe Pulvermacher tells 27 News that investigators are trying to determine who this crew works for and also the kind of work they were doing. Pulvermacher did not know an exact date, but says the crew was working near the site either the day of the explosion or a day or two before it happened. "It wasn't by MG&E crews. It was work that we had been made aware of," Pulvermacher explains. "I'm not entirely sure what that work entailed. I know it's something they took note of and is part of the investigation." Pulvermacher says investigators are speaking with the homeowner who was injured in the explosion to hopefully learn more about the crew that was working in his neighborhood.