Imphal, June 18 :    Imphal, June 18:  Ignited by fear for its territorial integrity, Manipur burned today as protesters demonstrating against extension of the Naga ceasefire poured their wrath on the Centre and politicians. In a spontaneous and devastating outpouring of anger that took the administration of Governor Ved Marwah completely by surprise, mobs torched the Assembly building, the chief minister's office and the Speaker's residence. Rough estimates suggest nearly 80,000 people were out on the streets of capital Imphal. By some silent consensus, they had decided to target only the seats of government - the Governor who is in charge by virtue of President's rule - and politicians. Today was the third day of protest against the Centre's decision to extend the ceasefire agreed with the militant National Socialist Council of Nagalim (Isak-Muivah) to areas in Manipur. Manipuris see the move as the beginning of an attempt to slice territories out of their state to be handed over to Nagaland as part of the demands of the NSCN(I-M) for a Greater Nagalim. Thirteen people were killed when the security forces, vastly outnumbered, opened fire. Over 30 were injured. Four MLAs and Speaker Sapam Dhananjoy, who was in his residence when it was set afire, were injured when protesters attacked them. Two legislators were trapped in the blazing Assembly building and would have been burnt alive had fire service men not rescued them on time. The Speaker finally took shelter at Raj Bhavan. Twelve bungalows belonging to legislators and former ministers as well as offices of many political parties were razed. 'Everywhere it is burning, burning, burning in Imphal,' a local resident told Reuters. Indefinite curfew has been clamped on Imphal and Greater Imphal as the Governor summoned top security officers and asked them to take measures to restore order. A.A. Siddiqui, director-general of police, said: 'Curfew has been imposed in the three districts of Imphal East, Imphal West and Thoubal. Security personnel have been told to shoot at anyone trying to create trouble.' Trouble erupted today when thousands of people marched towards Raj Bhavan from different directions carrying effigies of several Central leaders and NSCN(I-M) general secretary Thuingaleng. Muivah. When the protesters entered Imphal's VIP security zone and started burning the effigies, the tension escalated. The police first fired in the air to disperse the protesters without success. The mob - anywhere between 10,000 and 20,000 - chased the security personnel away and reached the gates of Raj Bhavan at 11.30 am, demanding an audience with the Governor. At noon, the protesters turned violent and first burned down the office of the Manipur State Congress Party. After that, they targeted offices of other political parties and ministers' residences. The offices of the Congress and the Manipur People's Party were also set ablaze. The office of the BJP was dismantled. The CPI and Samata offices were damaged. At 1 pm, the Assembly was attacked. In minutes, the building, which also houses the Assembly secretariat, was up in flames. Four MLAs, who were on the premises, were beaten up. Two - N. Bihari Singh and K. Tomba of the BJP, who had got trapped inside - were admitted to hospital with serious burn injuries. The security forces first fired on protesters when they attacked the chief minister's office and the residence of the Governor's adviser, K. Kipgen. Some other protesters had already set upon the official residences of MLAs and former ministers at Babupara VIP colony, adjacent to the chief minister's office and the state police headquarters. The official residence of the Union minister of state for food processing, Thonoujam Chaoba Singh, was gutted. Although security forces opened fire, they could not stop the mob from burning down houses of MLAs and former ministers. While three protesters died on the spot, 10 others succumbed to injuries in hospitals. The house of a Manipuri CRPF officer was damaged by protesters who accused him of issuing orders to open fire. The officer was in charge of the CRPF company which was guarding the chief minister's office and residence. In Bangkok, Muivah said the ceasefire agreement with New Delhi had nothing to with the demand for a Greater Nagalim comprising all contiguous Naga-inhabited areas, PTI adds. 'The ceasefire is a ceasefire' and 'at the moment it has nothing to do with territories,' he said.