An explosion on Monday blew up a large portion of a Trinamool Congress (TMC) party office in West Bengal’s Birbhum district but no one was injured in the blast, police said.“There was an explosion in a Trinamool Congress office in Birbhum district’s Kankartala at around 10.30 am on Monday. Large portions of the single-storey building was wrecked in the blast,” an officer from Kankartala Police Station said.“No injuries have been reported in the incident. The reason of the blast is yet to be ascertained.”Political blame game ensued immediately after the incident, with the TMC and the Bharatiya Janata Party (BJP) blaming each other for the explosion.Trinamool Congress’ Birbhum district chief Anubrata Mondal accused that some BJP-backed miscreants from Jharkhand were behind the blast.“The BJP has brought in goons from Jharkhand. They had been planning the explosion for past few days. Today they have succeeded,” Mondal said.Refuting the charge, state BJP leadership said that crude bombs stacked in the party office by the Trinamool workers caused the explosion.“Trinamool Congress has been making and storing bombs in the party office to terrorise locals. It seems that the explosion happened while making crude bombs inside the building,” state BJP president Dilip Ghosh said.The incident took place nearly 15 days after another office of the state’s ruling party in West Midnapore district’s Narayangarh was flattened in an explosion, killing two and injuring six others.