A federal grand jury has indicted a 58-year-old Prescott man on several firearms charges in what federal officials said was his plan to commit a mass shooting “to incite a race war” prior to the 2024 presidential election.

Mark Adams Prieto was indicted on firearms trafficking, transfer of a firearm for use in a hate crime and possession of an unregistered firearm, according to a release from the Arizona division of the U.S. Attorney’s Office.

The indictment alleges that, between January and May 2024, Prieto had discussions with two people working with the FBI “to devise a plan to commit a mass shooting of African Americans and other minorities to incite a race war” before the general election in November.

Prieto believed, according to the release, that the people he was working with “shared his racist beliefs.”

The targeted event was a concert in Atlanta that was going to take place on May 14-15.

The indictment further alleges that, having discussed specific details about the planned attack, Prieto sold two rifles to one of the individuals, an AK-style rifle on Feb. 25, and an AR-style rifle on March 24.

During the entire investigation, the FBI monitored Prieto’s movements, and on May 14 he was stopped by law enforcement driving east from Arizona through New Mexico along Interstate 40, authorities said.

Prieto was in possession of seven firearms and was taken into federal custody. Law enforcement then executed a search warrant at his home in Prescott. Law enforcement found more firearms in his residence, including an unregistered short-barreled rifle, according to the release.

Each conviction for firearms trafficking and transfer of firearm for use in a hate crime carries a maximum penalty of 15 years in prison, a fine of $250,000, or both. A conviction for possession of an unregistered firearm carries a maximum penalty of 10 years in prison, a fine of $250,000, or both.