Imphal, Jan 1 : Fresh violence rocked Manipur on the first day of the New Year with at least four people killed and 14 others injured by armed attackers in Thoubal district on Monday, police said. Police said that the incident occurred at Lilong Chingjao, where armed attackers opened fire at people following a quarrel over the forcible collections from the people. Among the injured, many are stated to be critical and shifted to hospitals. Reports said that the attackers, wearing police uniforms and armed with sophisticated weapons, came in four vehicles and opened fire on people, mostly Muslims. The three people died on the spot and another person succumbed to his injuries on the way to hospital. The identity of the killers is not known immediately. High tension followed the incident and two of the vehicles used by the assailants were burnt by an angry mob. Meanwhile, in wake of the Thoubal violence, the administration of all the five Valley districts -- Thoubal, Imphal East and Imphal West, Kakching and Bishnupur, cancelled relaxation of curfew and reimposed the prohibitory orders to prevent escalation of violence. Additional Central and state forces have also rushed to Thoubal district and adjoining areas where retaliatory attack could occur. Tensions have reportedly also risen in state capital Imphal following the fresh incident of violence. Chief Minister N. Biren Singh appealed for peace in the state and asked people not to take law into their hands and cooperate with the authorities. In a video massage, he condemned the attack and assured that the perpetrators would be apprehended soon. /IANS