A powerful bomb went off at Tiddim ground near Imphal airport here on Sunday, seconds after Army personnel in trucks passed the area.
Official sources said the bomb, an improvised explosive device allegedly planted by insurgents to attack security personnel, went off at around one pm.
They said the insurgents used remote-controlled device to explode the bomb.
The officer-in-charge of nearby Kwakeithel police station, accompanied by a police force, went to the area soon after the explosion and started a combing operation. No arrest was made.
No individual or group has claimed responsibility for the explosion.