At least three three Indian paramilitary police personnel were killed Friday in a landmine blast triggered by Maoist rebels in the eastern state of Orissa, news reports said, according to dpa. The blast took place when a vehicle carrying Central Reserve Police Force (CRPF) personnel was crossing a culvert in Orissa"s Malkangiri district, about 600 kilometres south-west of state capital Bhubaneshwar, NDTV news channel reported. Malkangiri district lies on the border of neighbouring Andhra Pradesh state and is part of a forested belt where the Maoist rebels are most active. CRPF commandant Bhupinder Singh was among the three killed, Malkangiri police superintendent Satyabrat Bhoi was quoted as saying. The CRPF is a federal paramilitary police force which is supporting local police in an offensive against the Maoists. The rebels are active in 20 of India"s 28 states and have been described by Prime Minister Manmohan Singh as the gravest internal security threat facing India. At least 2,671 people - including civilians, security personnel and rebels - have been killed in incidents related to Maoist violence in India since 2006, according to Home Ministry data. Maoist rebels claim they are leading an armed rebellion to secure the rights of India"s poor and marginalized people and operate in some of the poorest regions in the country.