JOHANNESBURG (AP) — Four white men in South Africa face treason and terrorism charges over an alleged plot that included plans to attack the ongoing African National Congress political party convention and kill President Jacob Zuma and others, authorities said Tuesday.

The organizers called their plan “the Slaughter of Mangaung,” using the ANC’s name for its meeting in the central city also known as Bloemfontein, prosecutors said. They planned to use mortars and machine guns to kill leaders, possibly at a dining hall the men previously took photographs of at the University of the Free State, where the leadership meeting is being held, officials said.