Spanish police arrest eight after three nights of violence in Torre Pacheco. Clashes pit far-right groups against North African migrants. Riots follow attack on elderly man by two foreigners speaking unknown language. Victim thrown to ground and beaten during cemetery walk. Two foreigners arrested for assault, main perpetrator still sought. Five Spaniards and one North African arrested for disorder, hate crimes, damage. Migrants comprise one-third of town's 40,000 population. Many migrants are second-generation or agricultural day laborers. Mayor urges migrants to stay home to avoid confrontation. Interior Minister blames far-right rhetoric and Vox party for linking immigration to crime. Violence organized via social media calls. Vox blames government migration policies. Similar 2000 riots in El Ejido after Moroccans killed three Spaniards.