Pretty much the same thing. I bet it started with a loose connection and just got hotter and hotter and spread out from there. As the initial part got hot, it increased it's resistance, causing even more heat and more resistance and more damage.
Ont thought to think about is that the actual buss will likely be overheated now, and that changes the amount of torque you can put on a screw head without easily stripping the screw threads. The original copper bus is tempered carefully to permit threading and once overheated, the mettalurgical properties change. You may have to replace the entire panel, or the inside bus bars if that has happened.
Send us some pictures...