Dibrugarh, Oct 26: Security forces today launched a massive operation in the forests around Khonsa in Arunachal Pradesh. The move follows an ambush by the NSCN (Isak-Muivah) on an Assam Rifles convoy last evening.

The attack had taken place around 7pm when a three-vehicle convoy, carrying personnel from the 23 Assam Rifles, was ambushed 3km off Panchau near Khonsa in Tirap district.

Tirap superintendent of police C.K. Mein said over telephone that the first vehicle, a truck, was blown up in a powerful improvised explosive device, after which the militants fired from both sides of the road.

Four persons died in the ambush. Three Assam Rifles personnel — havildar Mohan Singh and riflemen Luwang and S.K. Tiwari — were killed on the spot. Local businessmen Mukesh Srivastav died today.

Two jawans were critically injured. “One of the two injured Assam Rifles personnel was airlifted to the Indian Air Force hospital in Jorhat and the other to the army hospital in Dinjan. Their identity is not yet known,” an army source said.

The trader was with the convoy as he supplies materials to the paramilitary force operating in the district.

The attack comes at a time when the outfit is engaged in a ceasefire with the government to find a peaceful solution to the Naga problem.

“This is an unfortunate and shocking act of violence by the NSCN (I-M). We are still to make out why the outfit launched the attack,” a senior Assam Rifles official said. He, however, declined to give details.

Sources said the Naga militant outfit is believed to have carried out the ambush in retaliation to Operation Orchid, launched by the 23 Assam Rifles in the district to flush out NSCN (I-M) militants.

The twin districts of Tirap and Changlang used to be a stronghold of the Khaplang faction of the NSCN.

But since 2000, the Isak-Muivah faction has taken control of the districts, driving out most activists of its rival faction. The NSCN (I-M) claims the twin districts to be a part of the Greater Nagalim.

Sources in Khonsa said the army has joined the paramilitary force in the hunt for militants.