A federal grand jury has indicted an Arizona gun vendor for allegedly selling firearms to be used in a mass shooting he was planning in hopes of inciting a race war ahead of the 2024 presidential election, authorities said.

Mark Adams Prieto, 58, of Prescott was indicted Tuesday on charges of firearms trafficking, transfer of a firearm for use in a hate crime and possession of an unregistered firearm, the U.S. attorneys office in Arizona announced.

Prieto was taken into custody in New Mexico on May 14 after allegedly supplying rifles to an informant and an undercover agent while plotting out an attack on African Americans and other minorities at a concert in Atlanta.

According to federal prosecutors, Prieto told the individuals, who he met while selling at gun shows, that he hoped to kill as many people as possible and leave Confederate flags, Ku Klux Klan propaganda and other offensive rhetoric at the scene of the shooting in order to incite retaliation and start a race war.