Federal officials have charged four suspected members of a fringe Georgia militia with plotting to purchase explosives and produce the deadly toxin ricin in order to attack government officials as well as populated urban areas.

The four men arrested Monday were secretly recorded by an FBI informant as they discussed plans to obtain weapons and ricin with the intent to kill Justice Department officials and federal judges as well as agents with the Internal Revenue Service (IRS) and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF).

They also plotted to spread ricin, a highly toxic substance made from castor beans, across Washington, Atlanta, New Orleans, Jacksonville, Fla., and other cities, according to federal affidavits filed Tuesday.

"When it comes time to saving the Constitution, that means some people gotta die," an arrest affidavit quotes one of the defendants as saying during one recorded conversation. "I could shoot ATF and IRS all day long. All the judges, and the DOJ, and the attorneys, and prosecutors.”

The four men taken into federal custody were Frederick Thomas, Dan Roberts, Ray H. Adams, and Samuel J. Crump, all in their 60s or 70s. They appeared before a US magistrate in Gainesville, Ga. Wednesday afternoon.

“There’s no way for us, as militiamen, to save this country, to save Georgia, without doing something that’s highly illegal: murder,” the affidavit quotes Mr. Thomas as saying during a meeting in March.

Mr. Adams had worked as a lab technician at the USDA’s Agricultural Research Service. Mr. Crump once did maintenance work for the Centers for Disease Control. The two are accused of trying to obtain ricin for use as a weapon by spreading it on roads and having it dispersed by vehicles traveling along selected routes.

According to affidavits, the plot also included discussions about mass destruction and numerous casualties resulting from large explosive devices.

“We’d have to blow the whole building, like Timothy McVeigh,” one of the accused said, referring to the man convicted and executed in the 1995 Oklahoma City bombing that killed 168 people. "We gotta have a lot of explosives."

“Thomas, Roberts and others discussed the need to obtain unregistered silencers and explosive devices for use in attacks against federal government buildings and employees, as well as against local police,” the criminal complaint alleges. “Thomas, Roberts and others also discussed the use of the biological toxin that can kill individuals in small doses. The participants acknowledged that these actions would constitute murder but reasoned that the actions were necessary in accordance with their ideology.”

The arrests come at a time when militias and other home-grown antigovernment radicals declined as a threat in the years following the 1995 Oklahoma City bombing. For the most part, domestic terror plots since the attacks of Sept. 11, 2001, have been connected to radical Islam.

"While many are focused on the threat posed by international violent extremists, this case demonstrates that we must also remain vigilant in protecting our country from citizens within our own borders who threaten our safety and security," US Attorney Sally Quillian Yates said in a written statement announcing the arrests.

None of the four men charged in the case have criminal records except for driving offenses.

In 2003, a package was discovered at a mail-sorting center in Greenville, S.C., containing a letter and a small metal vial containing ricin powder. A year later, ricin was discovered in the mailroom of then-Senate Majority Leader Bill Frist. Three Senate office buildings were closed, displacing thousands of workers and raising echoes of a 2001 anthrax attack on the Capitol.

No connection has been found between those two incidents, and there have been no arrests.