Were you there? I was, so listen up.
It all happened really fast and everyone, including the CM's were confused. As soon as it was apparent the head was on fire and not going to go out on its own they stopped the show and made a general announcement.
This is Disneyland, so naturally everyone wanted to film this and have the breaking news and footage. Almost immediately after the announcement the CMs started trying to herd people out of there. You can hear it on one of my videos. I was standing in front of the Golden Horseshoe thinking it was far enough back. People were being very stubborn and stuck around filming when they were being told to evacuate.
They were sending people from NOS to CC up to Galaxy's Edge and the people on the Frontierland side up toward GE/Fantasyland. They were desperate to clear the path. Why? Because they don't have a fire engine hiding on TSI. CM's on the island tried to hose it down to no avail. They weren't expecting this to happen. Sirens were blaring all over Anaheim. I know this because people at the hotel I was staying at told us the next morning that they heard sirens for several minutes. They needed to get fire engines in there to take care of this and the closest they can get to is the area in front of NOS. To do that they had to clear out the stubborn video/picture takers. I believe the CMs were genuinely concerned there could be a gas explosion.
Of course there wasn't any footage of the fire department response because they cleared everyone out before they can let them in (most likely from the CC gate).
Disney responded as quickly as they could and God bless the CM's that had to deal with the people during the mayhem. They performed admirably and thankfully nobody was hurt.