Terror Threat At CBS Over Dancing Contestant

Sources at CBS tell TMZ, a note was attached to the white-powdery package that read something like, "This is what will happen to you if Bristol Palin stays on [the show]."

The white powder was later determined to be harmless -- but we're told law enforcement is still treating the situation as a credible threat, and is currently investigating the situation.

FYI -- this is the SECOND time Bristol has been targeted by a suspicious letter while appearing on "Dancing with the Stars." The first package was sent when Bristol first appeared on the show in 2010. It also contained a threat.