Having not been present at the CMASS fire I can only offer some general insight to put the incident in context and how to prepare.
In a sentence: Get the 4-person broom crew on foot to the fire right away.
If you were able to control the fire (stop the spread) before the fire dept arrived, that's a win in my book. Good work.
In most cases, the fire dept would first send in personnel on foot with hand tools (broom, fire rake, pulaski, shovel) to contain the fire. Its the fastest way to containment most of the time (if you can't drive right up to within 150 feet of the fire). That's why we CMASS put the 4 brooms on the trailer. Water is secondary [ go watch the first episode of Fire Chasers on Netflix. ]
If the day and weather are very high for fire risk, the best answer is cancel the launch. The 3 key factors are wind, humidity and fuel dryness.
I remember a summer launch in Acton during the drought. I was standing nearby a LP pad, dead calm, A-motor, normal launch. Just the flecks of BP propellant that bounced off the deflector onto the browned grass started a spot fire that was 5 foot across by the time the first broom got there. Its all about RESPONSE TIME.
Regardless of those factors, any day you are open to any random incident, be it a CATO, spot fire on the range, or a recovery gone wrong with a prang into a motor vehicle. So at some point the stats say you will have another incident. The many replies I read are 100% correct preparedness and training should be ongoing. I'll look into putting together a training and possibly a live burn session.
Since fire growth (spread) is exponential, TIME is the critical factor. Here is how your response should usually go out...
(1) If the fire is on the pad, send the water can first.
(2) If the fire is away (more than 150 feet), send on foot: 4-person crew each with a broom. Stop the spread. Sweep Towards The Fire.
(3) RSO/LCO - If it looks like the fire is going to go out of control, call the fire dept. The sooner you call them the less mad they will be.
(4) Then send 2 people with one water can. When person 1 is tired, person 2 takes over (or carry the can with a strap between 2 people).
(5) If its really far away, then put the 2nd water can, the fire rake, and all the coolers (emptied of contents) into a pickup truck. Drive to the nearest water source (stream, pond), and fill up all the coolers you have. Then go to the scene. In most cases, you need the water cans and more water to back up the 4-person broom crew.