Four persons were killed and over 50 injured when the police opened fire to disperse a demonstration organised by the All Assam Minority Students Union (AAMSU) that turned violent in Barpeta,a town in lower Assam on Wednesday morning. Official sources said that while three persons died on the spot,a fourth succumbed to his injuries after being shifted to the Guwahati Medical College Hospital here. The AAMSU had taken out the procession to demand a halt to a pilot project aimed at updating the National Register of Citizens. While over a thousand people under the banner of AAMSU marched towards the Deputy Commissioners (DCs) office in Barpeta to submit a memorandum,the crowd suddenly turned violent and started pelting stones at roadside shops and damaged vehicles even inside the DCs office compound. Barpeta SP Deba Jyoti Mukherjee said,The situation could be brought under control only by resorting to firing. The protesters would have burnt down the DC office and attacked the staff inside if we had not opened fire. Several policemen including the SP himself were injured in the stone-pelting.