So sad! The story said that the gar fireplace had just been serviced the week before but that was what caused the house to blow up. It sounds like someone didn't do a very good job.
I would guess with an explosion that size it was not the fire place as they thought. The readings done would have identified that.Gas lays low.....the tip off is the son in the basement. If he used a light switch or anything with spark and the gas was pocketed nearby, that was the mechanism to blow up.
From experience this seems like a leak that was through the system of gas into the home. it builds in the low lying part of the home. The odor is added to the gas as protection. Somewhere else in that home a pocket sat until a spark from an ignitor set it off.
The pipes coming in from the provider could erode, the connections coming in the house could have up-heaved from weather changes, rain, etc.
The fire marshal will have difficulty now, he will have to see where the worse damage area is and what appliance or pipes are there.
If the fireplace in fact were the issue, the family could not have stayed in the home without getting so ill they would leave. I think a slight odor came up through the pipes to the fireplace.
Somewhere lower lying the gas was collecting. It can even travel through the ground looking for a way to escape which could be their basement.
I worked on a case with an underground tank that the pipes into the home had shifted during yard work. In an attempt to empty the tank, the gas had already pooled into the basement near the entry steps. The owner came home, did not smell anything in the home, but did in the garage. He placed a dinner in the microwave walked out to talk to a repair man, and as left the entire near million dollar home blew out near the steps and garage, leveled the home and then burnt everything out.
A miracle he left the home, but the fire dept had a lot of explaining why the home was not checked for levels when they responded to the call.
Prayers for the family, speedy recovery, and I hope the son was gone out for the night too,
di