OTTAWA—Canadian authorities said they found and foiled a terrorist bomb-making plot by three men here—one allegedly with links to the conflict in Afghanistan and another, a pathologist who auditioned for the TV show "Canadian Idol.''

The Royal Canadian Mounted Police arrested the trio of Canadian citizens after raids on their houses turned up schematics, videos, drawings, books and manuals for making explosives, said Serge Therriault, Royal Canadian Mounted Police officer in charge of criminal investigations.

The...