Chief minister Mamata Banerjee on Sunday alleged “genocide” in Sitalkuchi, saying the four voters killed in Saturday’s CISF firing were “sprayed with bullets in the chest and neck”.

Her allegation came at an unscheduled news conference, called after her planned visit to Jorpatki village in Cooch Behar, where the deaths occurred, was thwarted by the Election Commission’s 72-hour ban from Saturday evening on politicians entering the district.

Mamata, however, sprang a surprise at the Siliguri news conference, making a 10-minute video call to talk to the bereaved families in Cooch Behar.

“This was genocide. It’s unprecedented. The central force just sprayed them with bullets,” Mamata had earlier told the reporters, adding that she had seen images of the bodies.

“They should have fired below the waist, but the bullets were fired at the neck and the chest,” the chief minister added, a black stole wrapped around her neck as a mark of grief and protest.

The dead voters — Nur Alam Mian (20), Maniruzzaman Mian (28), Samiul Haq (21) and Hamidul Mian (31) — are said to have been Trinamul supporters.

While the administration, functioning under the poll panel, has said the CISF personnel fired in self-defence after being attacked by a mob, local villagers have alleged unprovoked caning and firing by the forces.

Mamata questioned the deployment of the CISF, which specialises in industrial security, to maintain law and order during an election.

“Are they trained to control mobs? No. I want to know why bullets were fired like this. Why no tear gas? Why no water cannon?” she said.

Mamata continued to question the claim by the administration and BJP politicians that the CISF personnel had been forced to fire to protect themselves, their weapons and polling material like the electronic voting machines from a violent mob.

“Show me one (security force) person who was attacked and injured.... There is no basis to this self-defence theory,” Mamata said.

She accused the Centre of using the central forces and the Election Commission to create unrest in Bengal during the polls.

"It's an incompetent government, incompetent Prime Minister and incompetent home minister. They first kill people and then give a clean chit to those who killed them. I demand the home minister's resignation," the chief minister said.

She added: "They killed the villagers and then this order was issued to prevent me going there so that they can suppress the facts. But see, I can reach the family members there."

Mamata dialled the phone number of Partha Pratim Roy, Trinamul nominee from Sitalkuchi and president of the party's Cooch Behar unit.

Roy was at the morgue in Mathabhanga sub-divisional hospital where the families of the dead had come to collect the bodies after the post-mortems, whose reports have yet not been revealed.

During the video call, Mamata spoke to the families of Maniruzzaman and Hamidul and promised all possible help.

"You know that I wanted to come but they didn't let me. I shall come after three days, on April 14. I can't bring back those who lost their lives, but I shall do whatever I can for the families," Mamata told the grieving relatives.

Under Mamata's instructions, Trinamul observed a "black day" across the state. Party sources said Trinamul would continue the protests, portraying the Cooch Behar killings as a planned assault on Bengal by outsiders.

Union home minister Amit Shah, who attended multiple programmes in Nadia and North 24-Parganas, accused Mamata of using deaths to "pursue appeasement politics".

"The deaths are unfortunate, but the chief minister hasn't said anything about the fifth death. Ananda Burman, a first-time voter, was killed but she didn't say a word about him. She is using deaths to pursue appeasement politics for electoral gain," Shah said.

Mamata had, however, mentioned the death of 18-year-old Burman and said he was a Trinamul supporter.

News reports said Burman had been shot dead outside his booth in Sitalkuchi, at a place 15km from Jorpatki, during a BJP-Trinamul clash. The two parties have blamed each other.

Shah's allegation that Mamata had been silent on Burman was aimed at polarising the Hindu voters further, BJP sources said.