Four persons, including a police inspector, were killed in a landmine blast triggered by suspected Communist Party of India (Maoist) ultras at Dogadoha in East Singhbhum district of Jharkhand on Tuesday.

The landmine planted under a culvert went off killing the four travelling in a jeep, the police said.

A fierce encounter was on with the ultras in the area when the reports last came in. The Central Reserve Police Force and Jharkhand Armed Police have cordoned off the area.

The victims have been identified as Sushil Nag, Ghatsila circle inspector, his driver and two activists of the Nagarik Suraksha Samiti, an anti-extremism outfit floated by villagers and supported by the district police.