The victim family alleged that the miscreants attacked their house in Haridevpur area of Behala East constituency on Saturday night.
“They were angry as my father-in-law cast his vote earlier in the day. The attackers are Trinamool activists,” said the child’s mother Basanti Bor.
The child said she was reading a book when she heard people shouting outside.
“They were calling for my dadu (grandfather). Then they entered by pushing the gate, which struck me. Blood came out. Then they hit the same area with a baton. More blood came out,” said the girl.
The child was admitted to a local health centre, but later shifted to the state-run Vidyasagar Hospital when her condition deteriorated.
Some Communist Party of India-Marxist (CPI-M) supporters were also reportedly injured in the attack.
Kolkata mayor Sovan Chatterjee, the Trinamool candidate from Behala East, said the incident was “undesirable”.
“No one from my party was involved. But I must say such incidents are undesirable. It shouldn’t have happened. It has caused me great pain,” said Chatterjee.
Three people were arrested, said a police officer.
However, they later got bail from the police station itself.