Bengal Chief Minister Mamata Banerjee on Saturday sought Union Home Minister Amit Shah's resignation over the killing of four people in firing by central forces at Sitalkuchi in Cooch Behar.

Mamata, speaking at a public meeting at Baduria in North 24 Parganas, said she would be leaving for Cooch Behar after attending rallies, and would visit the spot where CISF personnel opened fire during polling in the fourth phase.

"Shah should resign owing responsibility for the incident which is dastardly, cold-blooded and unprecedented," the Trinamool Congress supremo said.

Four people were killed as central forces opened fire allegedly after coming under attack from locals, who "attempted to snatch their rifles", police said.

The chief minister said her party would bring out protest rallies throughout the state on Sunday, and asked TMC activists to wear black badges and demonstrate peacefully from 2 pm to 4 pm.

Mamata said she had long apprehended that central forces would act in such a manner. "As BJP knows it has lost the people's mandate, they are conspiring to kill them."

She alleged this was part of a conspiracy hatched by Shah.

"However, I would ask everyone to remain calm and cast their vote peacefully. Avenge the deaths by defeating them," Mamata asserted.

Later, at a press conference in Calcutta, TMC leaders termed the Cooch Behar incident as "pre-planned murder", and also called for the resignation of Shah.

TMC Lok Sabha MP Sougata Roy said the party condemns the unprovoked firing by central forces on innocent people.

"We demand the resignation of Home Minister Amit Shah. We want the Election Commission to come out with video footage of the firing to make people aware of the truth," Roy said.

"PM Narendra Modi and Shah cannot accept their imminent defeat in the ongoing elections in Bengal. This (firing incident) has happened at the behest of Amit Shah," senior TMC leader Subrata Mukherjee claimed.

Mukherjee said this was a "pre-planned murder committed to create panic among the common people" so that they become reluctant to cast votes in subsequent phases.

Chief Minister Mamata Mamata will visit the houses of the deceased, he said.

"TMC will always stand beside these hapless families," Mukherjee said.

Earlier, Mamata said the death toll in the Assembly elections has so far been higher than the panchayat polls held three years ago.

"Some 17-18 people have been killed since the elections began. At least 12 of them belonged to our party," she said.