At least 13 people were gunned down on Friday in a busy market area in a town in India's restive northeastern state of Assam, in the latest of a long line of violent incidents in the area.
The gunmen were wearing military uniforms to hide their identities, with Indian authorities accusing a regional separatist group of being responsible.
Unidentified attackers fired indiscriminately and threw hand grenades at the crowded weekly market in Kokrajhar – a town 220 km west of the state's commercial capital, Guwahati – eyewitnesses said.
One assailant was killed and security forces were in pursuit of around four others hiding in a nearby forest, Assam Police Chief Mukesh Sahay told reporters. Around 15 people were wounded in the attack.
Sahay said police had recovered an AK-47 rifle and explosives from the dead gunman, as well as a three-wheeler van the assailants had arrived in.
He blamed the outlawed National Democratic Front of Bodoland, Songbijit, a militant outfit fighting for a separate homeland for the indigenous Bodo tribespeople. The dead gunman was yet to be identified, said Sahay.
A senior Home Ministry official in New Delhi said preliminary reports indicated the attack, one of the deadliest in recent years in a region with a history of sectarian and separatist bloodshed, was carried out by the group.
"Police have launched a hunt to trace insurgents hiding near the incident spot. It is a militant attack and we will be sending a team from Delhi to investigate further," the official said.
Assam, a remote and underdeveloped state, has suffered from years of ethnic and tribal insurgencies.
"This attack is intended to destabilize peace in Assam," said Himanta Biswa Sarma, the state's finance and health minister.
Violence in Assam and the wider northeast has fallen as more militant groups have called ceasefires, although attacks by one community against another are not uncommon.
Deeply anguished by death of innocent people in dastardly attack in Kokrajhar district of Assam. It's senseless violence against humanity.
— ShivrajSingh Chouhan (@ChouhanShivraj) August 5, 2016
Militants fighting for a Bodo homeland killed at least 80 people, most of them tea-plantation workers from other parts of India, in a series of attacks in Assam in late 2014.
Police believe that a faction of the NDFB was behind the coordinated attacks on tea plantation workers and their families.
India sought cooperation from Bhutan, Myanmar and Bangladesh in an offensive against the tribal separatist group in 2014.