The Congress on Sunday attacked the Centre over the killing of civilians during an anti-insurgency operation in Nagaland, with Rahul Gandhi saying the government must give a "real reply" as to what is the home ministry doing when "neither civilians nor security personnel are safe in our own land".

At least 13 civilians were gunned down by security forces in Nagaland's Mon district, police said on Sunday, adding that it is investigating whether the incident was a case of mistaken identity. One soldier also died in the rioting which followed.

Reacting to the incident, Gandhi tweeted, "This is heart wrenching. GOI must give a real reply. What exactly is the home ministry doing when neither civilians nor security personnel are safe in our own land?"

Congress general secretary Priyanka Gandhi Vadra, in a tweet, said, "Heartbreaking news coming out of Nagaland, my deepest condolences to all the bereaved families. They deserve justice."

In a tweet from its official Twitter handle, the Congress said, "Tragic news from Nagaland is highly distressing. Repeated incidents of violence in North East is a clear indication of Modi govt's failure to maintain law & order & protect national security."

"PM & HM- why is Govt unable to ensure safety of our civilians & security personnel?" the Congress said.

The Army on Sunday ordered a Court of Inquiry into the killing of civilians and expressed deep regret over the incident.

Army officials said the operation in Mon district that borders Myanmar was carried out based on credible intelligence inputs about the likely movement of insurgents in the area.

It said the security forces suffered severe injuries in the operation and one soldier succumbed to injuries.