"The bomb planted by GNLA militants went off near the Nengkhra-Williamnagar road," Superintendent of Police J F K Marak said, adding that six policemen were travelling in a bullet proof truck when the incident happened.
"The blast was triggered 2-km from Nengkhra when the policemen were travelling from Nengkhra to Williamnagar," he said.
The bomb was placed under a culvert on the roadside and a flash gun of a camera used to detonate the bomb, Marak said.