LOS ANGELES — A federal grand jury yesterday indicted four men — including the leader of a state prison gang — for allegedly plotting a harrowing string of attacks against U.S. military facilities, synagogues and other sites in Southern California as part of a terrorist "war" by Islamic extremists.

The 15-page indictment accuses Kevin Lamar James, 29; Levar Haney Washington, 25; Gregory Vernon Patterson, 21; and Hammad Riaz Samana, 21, of plotting the attacks, using guns and explosives, to "maximize the number of casualties to be inflicted."

The six-count indictment names all four in a conspiracy to levy war against the U.S. government through terrorism and says the plot was hatched by James, an inmate at the California state prison in Sacramento and founder of a small prison gang of radical Muslims called Jam'iyyat Ul-Islam Is-Saheeh, or JIS.

James, the alleged mastermind, is serving a 10-year prison sentence for an armed robbery in 1996.

According to the indictment, Washington pledged his loyalty to James "until death by martyrdom" and sought to establish a JIS cell outside prison with bomb experts.

Washington, Patterson and Samana — who attended the same Inglewood mosque — allegedly conducted surveillance of National Guard facilities, the Israeli Consulate and several synagogues in the Los Angeles area as well as Internet research on Jewish holidays.

The attacks were to be carried out with firearms and other weapons on Jewish holidays, according to the indictment. Patterson allegedly bought a .223-caliber rifle in July.

The indictment also charges Washington and Patterson with robbing a gas station at gunpoint on July 5 to help fund the terrorism. Both men were previously charged by the Los Angeles district attorney's office in that robbery and nine others in Southern California.

While federal authorities have filed numerous terrorism-related cases in the United States since the attacks of Sept. 11, 2001, the vast majority have alleged that American citizens or foreign nationals have illegally attended terrorist training camps overseas or engaged in rhetoric or other actions that make them a potential security threat.

In this case, however, authorities have charged that a handful of men, all but one of them U.S. citizens, were raising money, purchasing weapons and conducting surveillance with specific plans to launch terrorism within the United States.

The FBI recently ordered its agents nationwide to conduct "threat assessments" of inmates who may have become radicalized in prison and could commit extremist violence upon their release.