An explosion outside a police station wounded five people in Assam on Thursday, police said.
The wounded included four civilian passers-by and a policeman who was sitting in a police vehicle that was damaged by the blast, said N Chaudhary, deputy superintendent of police.
No one claimed responsibility for the attack in Nagaon, a town 120 kilometres east of Guwahati.
All but one of those wounded were hospitalised, but their injuries were not life threatening, Chaudhary informed.
Police are investigating whether the blast was caused by an improvised explosive device or a grenade attack.
The area is a stronghold of a rebel group, the United Liberation Front of Asom, or ULFA.
At least 10,000 people, mostly civilians, have died in fighting in Assam state over the past 15 years between the government and rebels from ULFA and another separatist group, the National Democratic Front of Boroland.
Dozens of militant groups are operating in the impoverished region.