A rebel group has accepted responsibility for two of the seven recent explosions in the north-east Indian state of Assam.
Rebels set off explosives on a railway line
At least six people have been killed and another seven wounded in blasts since Wednesday night.
The United Liberation Front of Assam (Ulfa) said it had triggered off the blasts on a bus and a railway track.
Assam's rebels have been fighting a 25-year campaign for independence which has claimed more than 10,000 lives.
Ulfa chief Paresh Barua told the BBC by telephone that his group had set off two blasts, including one on a bus carrying Indian border police and their families in Goalpara on Thursday.
Three people, including the six-year-old daughter of a police constable, were killed in the attack.
Earlier on Thursday, two people were killed and more than 30 injured in a separate bomb blast on a passenger bus in Gossaigaon.
Police say there were fresh explosions on Thursday night at a market in Tangla and a railway track in Guwahati city.
Correspondents say the blast on the railway track, near an oil refinery, damaged the tracks and created a crater at the site.
In the other explosion, seven people were hurt when a grenade was hurled into the market.
Eighteen people, mostly women and children, were killed in a bomb explosion in the town of Dhemaji during an Independence Day march earlier this month.
Police blamed the attack on one of Assam's eight separatist groups.
The Ulfa had called for a boycott of Independence Day events.