Emergency vehicles on scene at CBS Television City outside of the studio for Dancing with the Stars. They were called to the scene after a suspicious white powder fell from a letter. (Photo: TMZ)

(TMZ) – Police and emergency vehicles arrived to CBS Television City in Hollywood just after 2PM today after someone reported that white powder spilled out of a letter in the CBS mailroom.

Law enforcement sources confirmed to TMZ that cops are investigating the scene.

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The suspicious, white-powder-containing letter was intended for “Dancing with the Stars” … law enforcement tells TMZ.

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

While there’s been controversy surrounding Chaz Bono‘s appearance on the show … sources tell us the target was NOT an on-air personality or contestant.

A rep for the FBI — which is investigating the matter — had no comment.

It’s not the first time CBS has had an anthrax scare — just last year, the studio went on lockdown when production staff found white powder in a letter addressed to Bristol Palin.

Officials also intercepted a threatening letter addressed to “Late Late Show” host Craig Ferguson just last month. The letter also contained white powder — which was later determined to be cornmeal.

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