At least three people, including two former ULFA militants, were arrested on Saturday in connection with the grenade attack at Sivasagar district in Assam.
The attack that took place on Thursday killed two people, news agency PTI reported quoting the police. Earlier in the day, the proscribed ULFA (I) had claimed responsibility for the grenade attack.
Eight people were picked up for questioning on Friday in connection with the incident at Demow area of the district, and three of them were arrested on Saturday. The trio also includes an employee of a petrol pump in Demow, police said.
A grenade had exploded at a hardware shop in the Demow Chariali area of the district on Thursday, killing a customer, Anup Gupta, and the shop owner, Kamal Agarwal.
Security has been beefed up in Guwahati, following the attack and reports of kidnappings in different parts of the state.
Deputy Commissioner of Police (Central) Ranjan Bhuyan said 17 suspected ULFA (Independent) linkmen have been picked up for interrogation from different parts of the city and all of them have previous criminal records and are accused of sheltering militants.
ULFA (I) Assistant Secretary Publicity and Information Arunodoy Asom, in a statement, said, "We take responsibility for Thursday's explosion and sooner or later stern action will be taken against those who betray us. But our target was not the customer Anup Gupta but the owner of the shop."
The banned outfit expressed condolences to Gupta's family, saying "our hearts go out to them". It however, denied any role in the killings of five people at Dhola in Tinsukia district on November 1, as claimed by the Assam Police and the National Investigation Agency (NIA).
Unidentified gunmen in battle fatigue had shot dead five Bengali-speaking individuals, including three members of a family, on November 1. "We had clarified earlier that the ULFA (I) is not responsible for the Tinsukia incident and we challenge the NIA to tell the people of Assam on what basis they are accusing us of the killings," Asom said in the statement.
Director General of Police, Kuladhar Saikia, had said on Thursday that the ULFA (I) was behind the Tinsukia killings.
According to the preliminary investigations conducted by the police and NIA, there was sufficient "technical evidence" about a six-member team of the ULFA-I being behind the Tinsukia firing incident, the DGP had said.
Regarding the ULFA (I) denial about its alleged involvement in the Tinsukia killings, the DGP had said the police were not paying any importance to the clarification issued by the banned outfit.