GUWAHATI: Assam remained on the edge on Wednesday as the death toll in attacks by the Songbijit faction of National Democratic Front of Boroland (NDFB) reached 76 amid reports of retaliatory strikes and thousands of people leaving their homes and taking shelter in schools and churches.

A day after the NDFB(S) attacks in Sonitpur and Kokrajhar districts, the Army and security forces stepped up counter-insurgency operations against the militants amid reports of Assam Police's failure to prevent the killings despite prior intelligence specifying date, time and location of the attacks. The state government insisted the intelligence inputs came too close to the attacks, allowing it little time to tighten security.

Retaliatory attacks began on Wednesday morning in which five Bodos were killed in Sonitpur and Chirang districts. Subsequent police firing to control hundreds of rampaging tribals claimed the lives of three more adivasis in Dhekiajuli in Sonitpur district. Adivasis beheaded two Bodos in Chirang and burnt down houses in Kokrajhar district. Night curfew was imposed in Kokrajhar, Chirang, Udalguri and Sonitpur.

More than 5,000 adivasis and Bodos left their homes and took shelter in schools and churches in Sonitpur and affected districts. Agriculture minister Nilamani Sen Deka, in Kokrajhar to oversee relief operations, said there were are about 3,000 inmates from both the communities in six relief camps in the district.

The National Investigation Agency will probe Tuesday's killings, said Union home minister Rajnath Singh after a meeting with Assam chief minister Tarun Gogoi here on Wednesday. Singh, accompanied by MoS home Kiren Rijiju, took stock of the situation and said Tuesday's massacre should be treated as an "act of terror". "The Union home minister directed security forces to deal firmly with the outfit and treat it as a terrorist group," a source said.

Defence PRO, Lt Col S Newton, said 10 Army columns, called in following a telephonic conversation between Prime Minister Narendra Modi and Gogoi on Tuesday night, were deployed in the troubled areas of Kokrajhar, Chirang, Sonitpur and Udalguri districts.

"Special area domination patrols have been deployed. Senior Army officers are supervising the operations and helping the civil administration and Assam Police," he said. Aerial surveillance by Army helicopters are in service, he added.

"We're going all-out against the militants. I had a discussion with the Prime Minister last night and the Centre has directed the Army to take out the militants," said Gogoi. "The Centre has also sent us 55 companies of paramilitary forces. The militants have taken shelters in Bhutan and Myanmar and Arunachal Pradesh," he added.

"Our immediate goal is to stop the violence. We are appealing to all sections of people to remain calm," Gogoi said, following retaliatory attacks by adivasis. Gogoi took strong exception to chief secretary Jitesh Khosla holidaying in Kaziranga National Park with his family since Tuesday.

Specific intelligence was generated by central agencies as well as the special branch of Assam Police about NDFB's Songbijit faction's plans to carry out strikes against adivasis and Santhals in Sonitpur and nearby areas around 4pm on Tuesday.

The alerts, which warned of serial attacks and killing of 100 non-Bodos to avenge the recent killing of NDFB militants by security forces came on Tuesday, hours before the militants struck.

Assam additional director general of police (special branch) Pallab Bhattacharya said there was information about strikes by NDFB(S) militants on Tuesday. "But we had no specific information about the locations," he said.

The Arunachal Pradesh home department issued directives to all deputy commissioners and SPs bordering Assam to keep vigil, chief minister Nabam Tuki said. "The home department has been instructed to act accordingly. All available paramilitary forces have been asked to patrol the border areas," he said.

NDFB(S) chief IK Songbijit, a Karbi tribal, is based in Myanmar and his outfit is seeking a sovereign state for Bodos out of the Bodo inhabited areas on the northern bank of Brahmaputra. In an interview to a TV channel, Ulfa leader Paresh Baruah, who has supported Songbijit, said, "Killing of civilians is part of any war strategy. This is part of war."