By Subir Bhaumik
BBC News, Delhi
The bombs caused chaos in a city that is normally peaceful (Pictures: Bapi Roy Choudhury)
At least four people have been killed in five bomb blasts in the north-east Indian state of Tripura, police say.
The explosions occurred in quick succession in busy markets in the state capital Agartala and injured 70 others.
"The markets were full of shoppers as the big Hindu festival of Durga Puja is only a few days away," said local journalist Syed Sajjad Ali.
Police in Agartala say timers were used to set off the bombs. It is not clear who might be behind the explosions.
"I was with my wife shopping at Maharajgunj bazar when one bomb exploded. I found seven people lying critically injured and called the police," Mr Ali said.
Witnesses say that two unexploded bombs were found in the town later, adding to the panic.
Many people were injured in stampedes that followed some of the explosions.
Tripura has a history of ethnic tribal insurgency - but explosives have rarely been used in crowded places.
It was not clear whether either of Tripura's two major ethnic insurgent groups, the National Liberation Front of Tripura (NLFT) and the All Tripura Tiger Force (ATTF), were responsible for the explosions.
Until now they have used explosives only to attack the security forces.
But they have attacked villages populated by Bengali settlers and killed many at a time.
Intelligence officials also say they cannot rule out the involvement of Islamic militants based in Bangladesh.