It alleged the group used the social network site for "inciting violence, targeting citizens, making bombs and carrying threatening messages."
It said one member called for the formation of an Islamic army and two others circulated names and pictures of police officers.
Egyptian authorities have cracked down heavily on the Brotherhood since the July 3 overthrow of President Mohammed Morsi, who hailed from the group. But today's arrests were some of the first to target alleged Brotherhood members for Internet activity.
