Kolkata, April 02 Widespread violence — bordering on the communal — shook parts of North 24 Parganas district on Wednesday after a mysterious fire in a madrasa in Naupara, Barasat sparked allegations of arson. Demonstrators choked roads, attacked police vehicles and also manhandled senior police officers who were at the spot to rein in the mob. Till reports last came in, a strong contingent, including columns of the Rapid Action force, was manning areas which were still smarting from tension. The fire took place in the Kharezi madrasa in ward 22 of the Barasat municipality. Locals said the mosque is over 100 years old. Just before the early morning prayers, dissenters said, certain miscreants entered the madrasa and set it on fire. Local residents doused it, but by then several manuscripts and religious material had been burnt, they alleged. Superintendent of Police, North 24 Parganas, Supratim Sarkar said: "It is difficult to say who is responsible for the fire but we hav