Definitely strange, I had it on that freq because like you mentioned, it's a fire frequency. I often park there and when I start to hear some agency out of Ohio I know the bands are coming up. Instead these guys were running around doing some sort of maneuver. You could hear the whine of the engine and a student being told where to turn and where to go.33.9 is a common fire dept freq and usually military comms in the US are confined to the even freq ranges like 32-32.975MHz, 34-34.975MHz, etc. Very odd.
Just like Lois Lerner and the IRS I can't find the recordings or I would post them here, well except for the fact that I'm actually not lying.
BTW, PRC I'm getting lots of stuff from out your way on 39 MHz tonight, lots of CHP.