Boom.

Regarding the natural gas odor noted by first responders upon arrival…chicken or egg problem…the gas lines probably fractured upon explosion. But, a gas leak could still cause the explosion.

The extensive frame fractures and complete devastation make a point source explosion an unlikely cause. That much energy (enough to damage adjacent homes) would seem to require a massive amount of fuel.

To have six people harmed would also suggest that all six did not notice a gas odor. I wonder if a stove was left on, after a meal prep, and overnight sufficient gas collected.