Large cities like that you are going to have SWAT and other groups training almost every day they aren't out on a raid. A lot of Alex Jones type websites make a big deal about these exercises but they are pretty routine. I have a friend in the local SWAT and he says they have these once or twice a week. Better than sitting behind a desk.
I have been working on a real estate deal yesterday and today with a Los Angeles Fire Dept./EMT friend and client. All this afternoon he has not responded to my text, which is how we communicate when he is working. My guess is that his unit may have rotated into a support role because of this emergency.
Guys like him are the very best. He served in the military as a medic. He lost friends trapped in a fire in Arizona; those guys that jump in behind the lines.