Gas leak?
That’s my guess.
Looks like
Hi.
Met lab, gas leak or a jihadi workman’s comp accident?
5.56mm
ATF doesn’t investigate gas leaks. I find it curious that they were there almost immediately, so gas leak has been ruled out or the occupants of this address are on a watch list
The gas company has to shut off the mains when a leak causes an explosion and they make announcements to that effect. Their pressure monitoring systems make gas caused explosions easily and quickly identified, plus everyone can smell the gas that will continue leaking till it’s shut off.