Another civilian was reportedly killed on Sunday while one was left seriously injured during the unrest in Nagaland's Mon after an angry mob of nearly 500 people vandalised the Assam Rifles camp situated in the district.

As per initial reports, the attack on the Assam Rifles camp triggered the security forces to open fire to control the mob.

The untoward incident occurred a day after violence erupted in Mon over the reported killings on Saturday by the security forces of Assam Rifles of 13 civilians in Oting village "mistaken" as insurgents.

The office of the Konyak Union, representing the dominant Konyak community in Mon, was also reportedly ransacked.

As the situation in the Nagaland district remains volatile, curfew has been imposed by the district administration, while, internet and SMS services have been suspended until further notice.

As per reports, a group of daily-wage labourers from Oting village were reportedly returning home from a coal mine in a pick-up van when they were allegedly fired at by the security forces, Superintendent of Police (SP) Imnalensa confirmed.

He further said that about 7-8 injured persons were admitted for medical care. Volunteers from the village had gone searching for them as they had not returned for several hours and found their bodies in the van, a local informed.

"Based on credible intelligence of likely movement of insurgents" a specific operation had been planned in the area, said the Assam Rifles in an official statement.

The statement added, "The incident and its aftermath is deeply regretted. The cause of the unfortunate loss of lives is being investigated at the highest level and appropriate action will be taken as per the course of law."

The operation was conducted based on inputs on the movement of militants of the Yung Aung faction of proscribed outfit National Socialist Council of Nagaland – Khaplang faction (NSCN-K), which is based in Myanmar, a police official said, adding that Nagaland's Mon shares a porous international border with Myanmar.