On Monday, the U.S. Department of Agriculture received “several anonymous messages that are concerning for the safety of USDA personnel and its facilities,” leading the department to close offices in five different locations.

As a precaution, USDA closed offices, until further notice, in Ft. Collins, Colo.; Hamden, Conn.; Beltsville, Md.; Raleigh, N.C., and Kearneysville and Leetown, W.Va.

These closures currently affect the following USDA agencies and offices at the locations: the Animal & Plant Health Inspection Service, Agricultural Research Service, Food Safety & Inspection Service, Forest Service, National Agricultural Library, Natural Resources Conservation Service, Office of the Inspector General and USDA Departmental Management.

“USDA is working closely with federal and local law enforcement, including the Federal Bureau of Investigation, to determine whether the threats are credible,” USDA director of communications Matt Herrick said. “Personnel at these locations have been made aware of the threats and will not report to these offices until further notice.”

The Associated Press reported that Agriculture Secretary Tom Vilsack, in an email to employees, said USDA is closing the offices “due to the serious nature of these threats” and added that Vilsack “did not characterize the threats or say how they were received but asked employees to be aware of their surroundings and report any suspicious activity.”