Emergency vehicles arrived to CBS Television City Wednesday, responding to a call that white powder was found in a letter in the CBS mailroom.
Sources told TMZ the letter was not addressed to anyone on "Dancing with the Stars," but it has not been determined to whom the letter was addressed.
Local radio KNX1070's Pete Demetriou tweeted, "#Whitepowder at CBS Television City not a threat."
CBS had an anthrax scare last year when production staff found white powder in a letter addressed to Bristol Palin, who was a contestant on "DWTS" at the time.
Last month, "Late Late Show" host Craig Ferguson also received a threatening letter containing a suspicious substance, which was later determined to be cornmeal.
UPDATE: Law officials told TMZ the suspicious, white-powder-containing letter was intended for someone on "Dancing with the Stars." Officials later determined the substance was not anthrax -- or any other harmful substance.