The FBI and the U.S. Postal Inspection Service are investigating suspicious packages that were sent to election officials in six states on Monday, the law enforcement agency said in a statement on Tuesday.

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.

Colorado's secretary of state says the poster of the letters called themselves the "US Traitor Elimination Army".