The blast, triggered by an improvised explosive device (IED), occurred at about 2 pm outside the gate of the BSF's Manipur sector headquarters at Koirengei on the Dimapur-Imphal highway, they added.
"The blast took place near a shop located close to the camp. The two slain constables -- Sanjay Tirkey and N Ningthouba Meetei -- were on a road protection task," a senior BSF official said.
The two jawans received splinter injuries in the blast, he added.
The three civilians injured in the blast were identified as Heishnam Muby, Mangshata Bam Premlata Devi (40) and Binbya Thakuri, a senior police officer said.
All the injured persons were rushed to the Regional Institute of Medical Sciences (RIMS), where both the BSF jawans succumbed to their injuries, he said, adding that the three civilians were undergoing treatment at the hospital.
The IED was suspected to have been planted by insurgents active in the area, the BSF officer said.
However, the police officer said no group had claimed responsibility for the blast.
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