At least four persons were killed in firing by federal security forces when a mob attempted to snatch their weapons outside a polling booth in election-bound West Bengal, triggering a blame-game between the eastern Indian state's ruling Trinamool Congress and Prime Minister Narendra Modi's nationalist Bharatiya Janata Party.

Police said that clashes broke out between a group of local residents and personnel of the para-military Central Indian Security Force in West Bengal's Cooch Behar district, following rumours that an aged man passed out after being thrashed by the federal troops at a polling booth in Sitalkuchi, about 680 km from state capital Kolkata.

"Actually the man who had come to vote fainted, and his treatment was going on across the booth. As rumours spread, locals thought he was beaten by the central forces. A mob soon gathered and tried snatching weapons from the federal troops," police officer Debasish Dhar told the local media.

In self-defence, the Central Indian Security Force personnel opened fire, in which four men, including a first-time voter, died, another police officer said. "The Election Commission of India has stopped polling at the booth in Sitalkuchi and sought a detailed report from the local administration."

Both the Trinamool Congress and the BJP were, however, quick to blame each other for the four deaths.

While Bengal Chief Minister and Trinamool Congress supremo Mamata Banerjee accused the central security forces of "planned murder" and demanded Indian Home Minister Amit Shah's resignation, Prime Minister Modi apparently attributed the clashes to the "goons of Trinamool".

"Home Minister Amit Shah is completely responsible for the incident and he himself is the conspirator. I don't blame central forces because they work under the Home Minister's order. We will demand his resignation," Banerjee said at a press conference in the evening, calling the deaths "murder by central forces".

On the other hand, Prime Minister Modi, currently campaigning in the state, slammed Chief Minister Banerjee and her party for the violence. "What happened in Cooch Behar is sad... I offer condolences to bereaved families. Mamata Didi and her goons are jittery because of groundswell of support for the BJP," he said.

However, Banerjee soon hit back at Modi. "The BJP knows it won't win so it's resorting to bombs and violence. The central forces are torturing people in villages. Women, boys and girls are being threatened that they should vote for the BJP. In the state election, 20 people have been killed so far and 13 of them are from our party," she said.

West Bengal is currently witnessing the most high-profile contest in India's ongoing state elections. While Chief Minister Banerjee has harped on being Bengal’s daughter, the BJP has been asking people to vote for "change and socio-economic development" after nearly 50 years of Communist and Trinamool Congress rule.