Italian police have detained a man caught on video head-butting a reporter from state-run RAI television amid an interview about his support for a neo-fascist movement.
The violence against the RAI journalist, Daniele Piervincenzi, has led newscasts in Italy for two days.
It has prompted calls by Rome's mayor for a march against organised crime this weekend.
Warning: This video may shock some viewers.
Mr Piervincenzi and his RAI cameraman were conducting interviews in Ostia after the neo-fascist, anti-immigrant CasaPound movement performed well in Ostia municipal elections on Sunday.
One of their subjects, Roberto Spada, who had voiced support for CasaPound, suddenly interrupted the interview, head-butted Mr Piervincenzi, chased after him and the cameraman and beat them with a stick.
CasaPound distanced itself from Mr Spada, who was detained today, and called for a full investigation.