A federal grand jury has indicted an Oregon man who authorities fear may have been plotting a sniper attack on a high school football game.

The indictment filed Friday in U.S. District Court in Medford charges 26-year-old Raphael Enrique Amoroso, of Grants Pass, with two firearms counts. One alleges he took a loaded .45-caliber pistol onto the grounds of Grants Pass High School. The other alleges he is an illegal marijuana user in possession of firearms.

He is scheduled to be arraigned Monday.

A judge ordered Amoroso held without bail after the prosecution argued that the case raised red flags suggesting he posed a danger to the community. Authorities cited a novel about a sniper attack on a football game found in his car, guns seized from his home and car, and past behavior.