On Friday members of the Latin American gang MS13 attacked a train manager trying to check their tickets on a State Railways train outside Milan. The man was attacked with a machete and the medics only narrowly managed to avoid amputating his arm.
The Italian police arrested three people, all of them from Central America.
The serious episode is likely to increase anti-immigration sentiments as Italy is struggling to cope with African immigrants crossing the Sicily Channel. Logistical problems led to some of them simply sleeping in railways stations, puzzling foreign tourists.
As the EU plan to have other Member States share at least partly the blunder drags on, Italy accused France of violating the Schengen rules by sealing its border.