CBS Suspicious Letter Addressed to 'Dancing with the Stars'

9/28/2011 4:32 PM PDT

The suspicious, white-powder-containing letter that triggered an emergency situation at CBS Studios in Hollywood today was intended for "Dancing with the Stars" ... law enforcement tells TMZ.

TMZ broke the story ... emergency vehicles were called to the studio after an unknown white powder spilled out of a letter inside the CBS mailroom.

Officials later determined the substance was not anthrax -- or any other harmful substance.

So far, it's unclear if the letter was intended for a specific cast member on the show.