There have been clashes between Indian police and political activists during municipal elections in Calcutta and an adjoining township.
Police used baton-charges to control the clashes between rival supporters, some of whom used swords, bombs and revolvers to attack each other.
Police said around 15 violent incidents left at least 70 people injured, among them several senior political leaders.
The polls will indicate party strengths ahead of state elections next year.
Some members of the ruling leftist coalition in West Bengal, of which Calcutta is the capital, were among those hurt in the clashes.