The U.S. Justice Department says four men have been arrested for an alleged plot to buy explosives and produce the deadly toxin ricin to attack citizens and the government.

In a statement, the U.S. Attorney for the Northern District of Georgia said two of the men sought to buy explosives and a silencer, while the other two took steps to produce the toxin.

U.S. Attorney Sally Quillian Yates said the four men — who range in age from 65 to 73 years old — are from the U.S. state of Georgia and suspected of being part of a fringe militia group. They were arrested Tuesday.

The Attorney's Office said the men began participating in clandestine meetings around March of this year and would discuss criminal activities including murder, theft, manufacturing and using toxic agents, and assassinations in an effort to undermine federal and state government and advance their interests.

It said they discussed using the biological toxin that can kill in small doses.

Authorities said the men met to discuss attacking various government officials and targets, and that those meetings were monitored by a confidential source who was working with federal officials.

The four men are to appear in court Wednesday.