Four people including a candidate in upcoming state elections have been killed by a bomb while travelling in a restive northeast region of India, police said Monday.

The blast tore through a car in Meghalaya state late Sunday as Jonathone N Sangma, a 43-year-old candidate for a regional party, travelled to a campaign event in the East Garo Hills district.

‘He was going to address a public meeting at a village. Three other persons in his car including a policeman and two civilians were killed,’ Challang Ch. Momin, deputy superintendent of Meghalaya police, told AFP.

‘We suspect that the bomb blast was an improvised explosive device. We haven't yet identified any suspects but we know that the last time he contested in 2013, he received threats from militants in the area.’

India's remote northeastern states, sandwiched between China, Bhutan, Nepal, Myanmar and Bangladesh, have witnessed decades of unrest.

The remote states, connected to the rest of India by a narrow strip of land, are home to dozens of tribal groups and small guerrilla armies demanding greater autonomy and resisting central rule.

Voters in Meghalaya will go to the polls on February 27 to elect a new 60-member state assembly.

Chief Minister Mukul Sangma vowed a speedy investigation into what he called a political assassination by suspected militants.

‘The blood of innocents spilled by the enemies of the state will not disturb the peace in Meghalaya. This desperate act will not be tolerated,’ the chief minister, who is of no relation to the victim, posted on Twitter.

Related Story