Ah, sorry. When an aircraft declares an emergency and requires the fire trucks (and EMS, etc.,) to be on standby as it lands, it is either an AC1 (Aircraft Concern level 1) or AC2 (level 2). Usually calls only go to level 2 with large amounts of people or fuel involved.. today's was a FedEx cargo jet coming in with reported flaps problems. Because he still had 18,000 pounds of fuel aboard (likely was passing through, not due to stop here), it was an AC2 even though there were only 5 people on board the 727.
An AC3 is a confirmed crash. I have worked two AC3s with my volunteer department, one in Kananaskis and one at the Springbank Airport. Everything from a hot-air balloon (crash-)landing in someone's backyard to an A321 digging a crater in the side of Mount Rundle could be an AC3.
Anyway, as far as the RCMP stuff goes, guess I'll have to monitor those freqs again. I haven't seen the RCMP ERT vehicles in ages (like 1993/1994 was the last time I saw them in action, IIRC); when I saw them then, the neatest thing I noticed was that they'd modified the hinges on the Suburbans' back doors so they could lift them off and leave them at the CP (command post), and drive in to the scene with no doors on, to give the team easier egress from the vehicle.
What we saw today during the AC2 was a very dark grey Airbus sized jet coming in on either runway 25 or 27 (the emergency was on 34). With Stampede going on and both Harper and Dion reportedly hanging around town, it's not a surprise that they'd be there.