To "Potential" above.
There was a group of about 12 or so guys and 2/3 girls who I saw at Phoenix before boarding, all with flight cases. I guessed they were trainee pilots.
I was in the rear cabin, seated at 45E, and there was deifnitely an evacuation ordered and it sounded to me to be the captain although it could have been another member of the crew. There was an alarm, a "nnnnnn-nnnnnnn-nnnnnnnn" sound.