Police in southern Italy have arrested more than 30 suspected members of rival Mafia gangs which are linked to the killing of six Italian men in Germany.
Police are focusing on organised crime gangs in San Luca
Hundreds of police raided the small town of San Luca, the focal point of a bitter feud between rival clans among the Calabrian Mafia, the 'Ndrangheta.
The town has been blighted by vendetta killings for more than a decade.
Police said brothers of two of the men killed outside a Duisburg pizza parlour on 15 August were among those arrested.
"The families that are fighting in Calabria are the same ones who fought in Germany," senior police officer Antonio Fiano told the Reuters news agency.
Reports said the camouflaged and armed police moved into San Luca, a hilltop town on the toe of Italy, before dawn, after prosecutors issued 40 arrest warrants late on Wednesday.
Three men were found hiding in an underground bunker hidden under a house, which was only penetrated when a special police unit used pneumatic drills to smash their way inside, says the BBC's David Willey in Rome.
Other raids uncovered sophisticated security and surveillance systems, Reuters reported.
Five women were among those arrested.
But the suspected killers were not arrested, with police saying the multiple arrests were necessary to prevent an outbreak of revenge slayings.
At least eight suspects remain on the run, police say.
"Presumably there was going to be a reaction, given that these two clans hate each other so much," a senior police official told the Associated Press news agency.
The murders in Duisburg took place after a birthday party celebration.
Police fear further killings in the 'Ndrangheta feud
The 'Ndrangheta, which is notorious for vendettas, is believed by police to control cocaine trafficking in many parts of Europe.
Membership of the 'Ndrangheta - which means "Honoured Society" - is believed to number in the tens of thousands.
The clan feud in San Luca, a town of about 4,500 at the southern tip of Italy, dates back to an egg-throwing incident in 1991.
A fight broke out which left two young men dead and another two injured.