The substance has been declared as harmless, but FBI is still investigating the case and FOX has hired extra security.
Khloe Kardashian has been targeted by a blackmailer. On Tuesday, November 20, a letter containing suspicious white powder was addressed to the reality TV star at CBS Studios, where "The X Factor (US)" is filmed.
FBI Public Affairs Specialist Laura Eimiller confirms that FBI, LAPD and L.A. Fire responded to a report of the suspicious package. "The item was field tested with negative results," Eimiller states, adding that FBI is investigating the case.
A source tells E! Online that Khloe "is fine" and "is not worried" by the incident. The source adds, "The studio has hired extra security. Khloe is heading to rehearsals right now." Another source tells TMZ that the package contains a letter, but it's unclear what's written.
FOX, which airs the U.S. version of "The X Factor", hasn't commented on the suspicious package.
It's not the first time CBS Studios receives such package. Bristol Palin was targeted with similar package during her stint on "Dancing with the Stars", which is also filmed in the studio.