Jean released levels of radiation that caused organic material to literally burn away, seen most abundantly at the point when Jean was beginning to discorporate the planet, stripping it down to its primal components in the next stage of her evolution at the film's conclusion, as detailed in the screenplay. So in theory, yes, she was building to a massive molecular conflagration that was witnessed on a small scale by basically rendering any in her way to mere clouds of ash.
If you're referring to the mutant who could sense the powers of other mutants and was possessed of heightened strength, speed, and agility, that was Callisto.
Psylocke was the young Asian girl with streaks of purple through her dark hair, standing next to Callisto in the Church, spouting the line, "They want to exterminate us!"
Also, yes, a large portion of the Brotherhood in X3 were the Morlocks, led by Callisto and tattooed with the Greek letter Omega (symbolizing the end times, and that it would be the end for any who stood in opposition to them).
I hope this helped to clear some things up.