Calcutta, June 14: Four Trinamul Congress workers were hacked to death on their way home in South 24-Parganas tonight, the assailants dragging them out of autorickshaws on a dark stretch during a power cut.

Trinamul accused the CPM of the attack in Raidighi, an Assembly seat the ruling party’s Debasree Roy snatched from Left veteran Kanti Ganguly in one of the biggest upsets in the elections. The Left party, however, said the massacre was the fallout of Trinamul factional feud, a claim police did not dismiss immediately.

Sources said this was the biggest toll in political violence in the state since the Mamata Banerjee government came to power.

The police said that according to reports available with them, the 12 Trinamul workers could have been returning from a kangaroo court in two autos when they were attacked around 10.30pm at Kharighosher Chowk near Saraswatipara, 80km from Calcutta. The law-enforcers said the Trinamul workers could also have been returning from a booth-level meeting.

The assailants, who allegedly hurled bombs to scare away passers-by, waylaid the two autos, dragged the Trinamul workers out and hacked them with choppers.

Four Trinamul workers — Hossain Gazi (40), Atiyar Mollah (32), Ayush Mollah (33) and Hassan Sheikh — were declared dead on arrival at Raidighi rural hospital. The eight others are being treated there. Doctors said the condition of four of them was critical.

Police sources said the attackers were waiting near a boundary wall. A sub-inspector of Raidighi police station said the attacks did not seem to be the fallout of a possible visit to a kangaroo court.

Trinamul secretary-general Partha Chatterjee said: “The CPM perpetrated the pre-planned attack on our party workers.” Chatterjee and Trinamul all-India general secretary Mukul Roy will visit Raidighi on the instructions of the chief minister, party sources said.

C.M. Jatua, the Trinamul MP from Mathurapur under which Raidighi falls, also pointed fingers at the CPM.

The CPM denied the charge, saying the attack was the fall-out of Trinamul’s factional feud.

Sources said tension had been brewing between Trinamul and the CPM in Raidighi for the past few days. Although Jatua won the seat by a margin of over 1.38 lakh votes, the CPM candidate bagged over 4.8 lakh votes.

Director-general of police G.M.P. Reddy has sought a report from the district police chief on the murders.