Members of the group called Hutaree are charged in the case, including their leader, David Brian Stone, also known as "Captain Hutaree."
Once other officers gathered for a slain officer's funeral, the group planned to detonate homemade bombs at the funeral, killing more, according to newly unsealed court papers.
The indictment includes charges of seditious conspiracy, possessing a firearm during a crime of violence, teaching the use of explosives, and attempting to use a weapon of mass destruction -- homemade bombs.
The indictment charges members of the group conspired "to levy war against the United States, (and) to oppose by force the authority of the government of the United States."
The charges follow FBI raids over the weekend on locations in Michigan, Ohio, and Indiana.
According to investigators, the Hutaree view local, state, and federal law enforcement personnel as a "brotherhood" and an enemy, and planned to attack them as part of an armed struggle against the U.S. government.
Eight suspects have been arrested by the FBI, and one more is being sought. Of the eight captured, seven are due in court later Monday.
Andrew Arena, head of the FBI's field office in Detroit, said the case "is an example of radical and extremist fringe groups which can be found throughout our society. The FBI takes such extremist groups seriously, especially those who would target innocent citizens and the law enforcement officers who protect the citizens of the United States."