GUWAHATI (Agencies) - At least 61 people were killed and 470 injured Thursday in over a dozen blasts that ripped through towns and markets in the insurgency-hit northeastern Indian state of Assam, police said. A police spokesman confirmed a total of 13 blasts within the space of about one hour, five of them in the state's main city of Guwahati. Three other districts in western Assam were also targeted. There was no immediate claim of responsibility, although state officials said the bombings were probably the work of the rebel United Liberation Front of Asom (ULFA), which has been fighting for an independent homeland since 1979. "This is an act of cowardice... designed and carried out to spread terror," Assam Chief Minister Tarun Gogoi said. "We shall deal with the situation firmly," he said. The state's home commissioner, Subhas Das, put the death toll at 48, with 25 of the fatalities in Guwahati, where the blasts targeted busy market areas, including one close to the high security secretariat and state assembly. An immediate curfew was clamped on the city as angry residents went on a rampage, attacking police vehicles and public buses. "The area was teeming with people, office workers, shoppers and vendors when a very big explosion took place," said witness Arindam Das, who was shopping in one of the markets. "I saw at least six dead bodies, while more than 30 people were lying on the ground and bleeding," Das said. One of the blasts took place in front of the Guwahati District Magistrate's Court, killing five people. "Some of the bodies were charred beyond recognition," Deputy Inspector General of Assam Police GP Singh said. Eleven people were killed in three explosions in the western district of Kokrajhar and 12 in nearby Barpeta district. "It is very early to make a conclusion but ULFA has a history of triggering serial blasts," Assam's Health Minister Himanta Biswa Sarma was quoted as saying by the Press Trust of India. "Most of the bombs were planted in crowded places like markets and office complexes. So it shows that the perpetrators wanted high casualties," Sarma said.