By Subir Bhaumik
BBC News, Calcutta
At least 15 people have been injured in a bomb explosion outside a tea stall in the town of Tinsukia in the north-east Indian state of Assam, say police.
Violence has escalated in Assam since last September
Four of the injured are reported to be in a critical condition.
On Thursday, two people were wounded in a blast at a storage warehouse of the government-owned Food Corporation of India in the state capital, Guwahati.
Assam police chief RN Mathur has blamed the separatist United Liberation Front of Assam (Ulfa) for both explosions.
Ulfa is fighting one of India's longest-running insurgencies to establish an independent homeland in Assam.
Mr Mathur said most of those injured were Hindi-speaking migrants, who have been targeted by Ulfa rebels since the beginning of this year. More than 80 migrants have died in the attacks.
"The tea stall was frequented by the Hindi-speaking migrants. They would come here for breakfast," Mr Mathur said.
Ulfa has been on the defensive since the Indian army intensified its operations against the separatist group.
Many Hindi-speaking migrants have fled
More than 30 rebels, including some of their top field commanders, have been killed in encounters over the last month.
Three Ulfa members were killed on Thursday and a top commander, Ananta Gogoi, was arrested in Guwahati on Monday.
The rebels, who say the migrants are "the evil shadow of the Indian state in Assam", have hit back with periodic bombs targeting them.
Last month, Ulfa kidnapped PC Ram, the regional director of the Food Corporation of India.
Police says the rebels have asked for 200m rupees ($4.8m) for Mr Ram's release.
Talks between the Ulfa and the Indian government broke down last September when the rebel group insisted on including Assam's sovereignty as the key issue in the negotiations.
The Indian government on its part insisted on a ceasefire and an end to violence.