At least four paramilitary Central Reserve Police Force (CRPF) troopers were killed and 15 injured, four of them critically, in a powerful landmine explosion Friday in Holmari in Assam's Goalpara district.

Militants, suspected to be from the outlawed National Democratic Front of Bodoland (NDFB), triggered a landmine blast around 8 a.m. when around 20 CRPF troopers were returning in a bus from an anti-insurgency training camp.

The landmine was planted in the middle of a road surrounded on either side by thick forests in Goalpara district, about 130 km from Guwahati.