India, Aug. 21 -- At least five people, including a woman, were injured in a blast at a firecracker unit in West Bengal's South 24 Parganas district on Thursday, police said. The explosion took place at the factory in Champahati area around noon, following which a fire broke out at the unit, a senior officer said. Two of the injured were stated to be in critical condition, while three others were treated at a nearby hospital and later discharged, officials said. A probe has been launched to ascertain the exact cause of the blast and verify whether the unit had the requisite licence and was following safety norms, the officer said. According to locals, firecracker-making activities were being carried out in a makeshift structure on a plot ...