The Uncanny X-Men #489

Masque has disfigured a subway car full of humans and posted a movie on the internet warning humans that the few remaining mutants left are weapons aimed directly at them. Storm uses the FF's resources to track the Morlocks. Sentinel Squad O*N*E soldiers reach the Morlocks first and are brutally murdered. The X-Men arrive after the carnage is complete and find Skids still alive buried under some rubble. When the X-Men are attacked by a Sentinel, Skids tells it to stand down and reveals that she is an undercover agent of SHIELD.