BBM
I don't think we know much... but IMO the being at firefighting training kind of evolved (without any substantiation) from "in Denver," to "in Denver for work," to "in Denver for Fire Fighting training".
JMO, IMO, MOO
And, like anything posted here without a giant IMO will take on legs and run. Like, "Why was he in Denver?" "He could have been in Denver for work." "But he's a volunteer FF, so why would he need to be in Denver for work?" "Oh, it could have been training." "Oh, so he was in Denver for firefighting training; got it." "So, husband claims he was in Denver for FF training." I watched it happen.
JMO, IMO, MOO