The Indian government on Monday tightened security along its porous frontier with Bangladesh suspecting the involvement of foreigners in the twin blasts in Assam that killed 14 people even as a separatist bomber linked to the explosions was shot dead by police.
"We know the United Liberation Front of Asom (ULFA) was behind the bomb blasts in Guwahati. We are trying to find out if they have been backed by Islamist militants in neighbouring Bangladesh," said a senior intelligence official in New Delhi.
A police spokesman in Assam said a four-member team of ULFA rebels challenged a security team near Patharquarry, one of the two locations of Sunday night's blast, on the outskirts of Guwahati.
"There were four rebels taking shelter in a farmhouse and when we reached the spot they challenged us with grenades. We retaliated and the encounter lasted for more than 30 minutes," said Rajen Singh, deputy police chief of Guwahati.
"One of the militants was killed and the other three managed to escape. We believe the dead rebel to be one of the bombers involved in Sunday night's explosions," Singh said.
The joint police and paramilitary team recovered 12 grenades and some explosives from the dead militant. Police in two separate raids arrested 12 ULFA supporters from Guwahati city on Monday.
Two powerful explosions rocked Guwahati one after the other Sunday evening - one at the crowded Fancy Bazaar area and another at Patharquarry on the city outskirts. Fourteen people were killed and 38 wounded in the blasts.
The ULFA is yet to own up the bomb attacks.
Rattled by the explosions, the Assam government held a series of high-level meetings. A meeting of the Unified Command Structure to review the security situation is to begin on Monday evening.
"A composite team of the union home ministry is arriving in Guwahati to take stock of the situation and work out strategies," Assam governor Lt Gen (Retd) Ajai Singh told reporters.
Union Home Secretary VK Duggal will chair the meeting of the Unified Command.
"This is nothing but an act of desperation with the ULFA killing innocent civilians. We are stepping up security and take all possible steps to thwart possible rebel attacks," Chief Minister Tarun Gogoi said.
Both the chief minister and the governor visited the injured in hospitals.
"The twin blasts have caused panic and people are now scared to even move out of their homes," said Ram Bharatiya, a textile merchant in Guwahati.
"The bomb at Fancy Bazaar was kept on a bicycle and this is one of the latest modus operandi of the ULFA to keep explosives to target innocent civilians," said Assam Police (Intelligence) chief Khagen Sharma.
Meanwhile, a dawn-to-dusk general strike Monday to protest the separatist bombings hit normal life in Guwahati.
Markets in the city remained closed and the streets wore a deserted look.
The 12-hour strike that began at 6 am was jointly called by the opposition Bharatiya Janata Party, the Kamrup District Chambers of Commerce and the Purvottar Hindustani Sammelan - a socio-cultural group of Hindi speaking people in Assam.