At least eight persons including five policemen and three poll officials were killed when the vehicle they were travelling in was blown up by the Maoist rebels in Central state of Jharkhand, police said Friday. Police said the incident happened on Thursday night in Dumka district of Jharkhand after the policemen and polling officials were returning from the poll duty. Police told media that the eight persons were killed after Maoist rebels triggered a landmine blast targeting a vehicle, adding, nine more people were injured in the incident. The police informed that the injured persons have been hospitalized. They further stated that the additional forces have been sent to the spot to hunt down the culprits. Senior police and administrative officials too have reached the spot to take stock of the situation, police added. The earlier two phases of parliamentary elections in the state were held peaceful. The nine phased Indian elections to elect the new parliament is currently underway in the country and would conclude on May 16. The authorities had already declared Jharkhand as a poll sensitive state and had made strict security arrangements to secure polling stations in the area. The Maoist rebels are active in 83 districts spread across nine states of India.Maoist rebels have been fighting in several Indian states for more than 40 years claiming they have been inspired by the Chinese revolutionary leader Mao Zedong. Indian Prime Minister Manmohan Singh has described the Maoist rebels as India's biggest internal security challenge