American citizens could be targeted by extremist groups in Italian cities over Easter, the US State Department has warned. The US did not identify the groups or nature of the attacks, but said the cities at risk were Florence, Venice, Verona and Milan. A US official quoted by Associated Press said the warning was based on "very specific information". "These groups do not distinguish between official and civilian targets," the State Department warned. Places of worship, restaurants, schools and outdoor events, were among the possible targets mentioned by officials.