At least six personnel from the Odisha State Armed Police were killed and several others were injured after a landmine exploded under a culvert on a road in the Koraput district of the state. Koraput District Superintendent CS Meena said the blast took place on a mountainous section of National Highway 26 at the Mungabhumi village near the Odisha-Andhra Pradesh border, The Indian Express reported.

The bus carrying the personnel was flung at least 60 feet down the mountain road, according to the report. The bus was taking members of the force to the Angul Police Training College when the incident took place, Deccan Chronicle reported. Police officers and Border Security Force jawans conducted rescue operations at the site and transported the wounded to local hospitals.

The blast also led to hundreds of vehicles being stranded on the section of the highway connecting Koraput with Vishakapatnam.

The incident comes just two weeks before three-tier panchayat polls in the district, which Maoists in the Malkangiri region have wanted the public to boycott. Officials said the blast was the rebel group’s retribution for an encounter between their cadres and security forces in Malkangiri. At least 27 Maoists were killed in the October, 2016 encounter.