Here’s a video of a Cutler-Hammer panel fire. This is a licensed electrician.
Just watch him pull the breakers while the panel is still energised.
He’s obviously never been exposed to an arc-flash or seen a plasma burn.
https://www.youtube.com/watch?v=cgQ8CPkx9bM)
If you EVER see this, throw the main disconnect and call a Licensed Electrician or Electrical Inspector. Don’t just write it up in your report.