The National Democratic Front of Bodoland (NDFB) activists are suspected to have triggered the blast.
Four buses of the CRPF were also targeted by the militants.
According to the sources, CRPF personnel were patrolling the area when the unidentified militants set off the explosion at 8 am.
On Thursday, Jul 29, at least 12 persons, including a woman and two minors were injured in a dynamite blast in a private stone quarry at Jorabat on Assam-Meghalaya border.
This is the second attack on security forces in Assam in a week.