Two suburban Chicago men have been indicted on charges accusing them of plotting a terrorist attack on an Illinois military facility.

Hasan Edmonds is a 22-year-old member of the Illinois Army National Guard. He and his 29-year-old cousin, Jonas Edmonds, were arrested last month for allegedly conspiring to provide material support to the Islamic State of Iraq.

The indictment was filed Thursday in U.S. District Court and announced Friday. Prosecutors say the two men will be arraigned April 8. The men are U.S. citizens and residents of Aurora.

Prosecutors allege Hasan Edmonds sent Internet messages vowing to "cause as much ... mayhem as possible." The alleged plan was for him to travel abroad to join Islamic State fighters while his older cousin attacked a military installation in Illinois.