The FBI is warning election offices to be on the lookout after threatening letters containing suspicious substances were sent to the offices of multiple secretaries of state throughout the country.

Suspicious packages were sent to election officials in at least five states, but there were no reports that any of the packages contained hazardous material

The Federal Bureau of Investigation, along with the U.S. Postal Inspection Service, are investigating suspicious packages that were delivered to election officials in several states, according to officials.