Five people, including a Congress panchayat candidate, were arrested from a house in West Bengal's Birbhum district where crude bombs were allegedly being made, police said on Saturday.
Acting on a tip-off, a house in Bahirgora village in Margram police station area was raided around midnight, they said.
Crude bombs were being made on the roof of the house, they claimed.
Those arrested were Chamatkar Seikh, a Congress candidate in Hasan-II panchayat, the owner of the house Sheikh Tom, and Ghiyasuddin Sheikh, Duke Sheikh and Anarul Sheikh, police said.
Police said they have seized some crude bombs, and materials that were being used for making them.
A case was lodged and an investigation is underway, they said.
West Bengal's rural areas will be voting for the panchayat polls on July 8.
Earlier in the day, one person was killed and three were injured after a crude bomb went off in a mango orchard in Murshibabad district, police said.
Alim Sheikh, 26, who was critically injured in the blast, was rushed to a local hospital where he was declared dead.
The three others are being treated for injuries in the same hospital, police added.
Sheikh, who hailed from Kapasdanga village in Beldanga, was a history-sheeter, police said.
In another incident, three persons sustained minor injuries after crude bombs were hurled during a clash between Trinamool and Congress activists at Raninagar in Murshidabad, police said.
The incidents triggered a war of words between the ruling and opposition parties with the Bharatiya Janata Party and the Congress accusing the Trinamool of engaging criminals to make crude bombs to spread panic in the run up to the July 8 panchayat polls.
BJP national vice-president Dilip Ghosh said the incidents reveal TMC's bigger game-plan to intimidate opposition candidates and prevent their supporters from going out to vote.
WBPCC president and Berhampore MP Adhir Choudhury said, "Miscreants sheltered by the TMC are making bombs to trigger widespread unrest ahead of the rural polls. We don't have faith in police as they are not taking action against local-level Trinamool leaders."
TMC state spokesperson Joy Prakash Majumdar said the number of deaths and injuries from such incidents has gone down drastically since the party came to power in 2011.
Majumdar said there was no evidence to prove TMC's involvement in the Beldanga incident and claimed that the opposition was levelling false charges against the ruling party.
He accused the BJP and the Congress of engaging miscreants of making bombs to create disturbances and show the state in poor light.
Widespread violence over the filing of nominations for the three-tier panchayat polls has left at least eight people dead and several injured in various parts of the state in the past two weeks.
