A bomb blast in India's northeast on Thursday killed at least five people and wounded another six, police said.
Officer Bani Brata Basu said the explosion occurred near Jalpaiguri, a town nearly 700 kilometers (440 miles) north of Kolkata, the capital of West Bengal state.
Police are investigating whether the blast was carried out by any rebel group fighting for independence or wide autonomy in the region.
The Press Trust of India news agency quoted Officer Shashikant Pujari as saying the bomb was rigged to a bicycle.
Pujari said the explosion might have been carried out by the Kamatpur Liberation Organization, an insurgent group which was observing a "Martyrs' Day" in memory of its members who have been killed by government forces.
Separatists accuse the Indian government of exploiting the natural resources of the northeastern region while doing little for the indigenous people, most of whom are ethnically closer to the people of Myanmar and China than to other Indians.