Some agriculture department offices are closed until further notice.

FOX's Gurnal Scott has the story:

AG secretary Tom Vilsack says local authorities are working with the FBI to determine the credibility of the anonymous threats. Six offices in five states: Maryland, Connecticut, North Carolina, Colorado and two in West Virginia are closed for now.

White House Spokesman Josh Earnest says the investigation is ongoing:

(Earnest) "We take that quite seriously and we place the safety of those workers at a high priority."

Neither the the White House nor the USDA are giving specifics, but are asking employees to be aware of their surroundings.

Gurnal Scott, FOX News.

Follow Gurnal Scott on Twitter: @GurnalScott