One of the injured, 14-year old Purnima Rojok (14) succumbed to her wounds at the Assam Medical College Hospital where the other injured were admitted, the sources said.
Preliminary investigations pointed to a crude bomb and not a grenade as no splinters were found at the site of the blast and also there was no trace of an improvised explosive device (IED), Bhuyan said.
The identity of the insurgent outfit responsible for the blast was not immediately known as investigations were on, the SP said.
The explosion created a two feet wide crater on the road, the sources said. Local people had reported to police that two extremists came on a motorcycle and hurled a grenade before fleeing away.
Senior police officials have rushed to the site, cordoned off the area and tightened security arrangements in the town. Both ULFA(Independent) and Maoist elements are known to be active in upper Assam, sources said.
Earlier on December 15, a grenade was exploded by suspected anti-talk NDFB(Songbijit) at Molandubi Market in Kokrajhar district killing one person and injuring four others.