 Complete the following phrase:  Rivalries with other teams have escalated into serious violence. A group of ultras who label themselves the Fedayn  the devotees  after a group of long-forgotten Iranian guerrilla fighters are regarded to be responsible for the organised hooliganism. In 2014 Daniele De Santis, a Roma ultra, was convicted of shooting Ciro Esposito and two others during clashes with Napoli fans who were in Rome for their clubs 