“Could the RV have been used as a visual shield? Park it next to or partially over a grate before opening the grate? Kind of poor security though if grates could just be lifted open.”
Yes, that actually occurred to me when someone mentioned the doors being blasted from inside. The grates could have been locked, but broken into to place charges - the placement of the RV adjacent to them could have been used as a shield.
I’m still not clear on where everything was located.
The underground cable runs “could” have also been filled with gas and ignited by something topside - or an explosive charge. One of the rules of underground cable is that you always ventilate with a blower before entering a confined space. Doesn’t correlate well with the announcement, though.
(I was a Southwestern Bell cable splicer in a former life, but didn’t work in underground a lot. Mostly buried and aerial, with a number of months spent in central office cable vaults.)
I’d like to hear from someone with explosive expertise about the sound of the explosion itself and the visual appearance.