Armed militants surrounded a busy market in India's mountainous north-east and fired into the crowd, killing at least 12 people and wounding 13.
The violence is not related to the recent build up in tension between India and neighbouring Pakistan.
Two groups of militants of the outlawed National Liberation Front of Tripura surrounded the market in Singicherra in the remote Tripura state and opened fire. The militants then escaped. Hundreds of police launched a search for the assailants.
The wounded have been admitted to hospitals in the state capital of Agartala, where 10 are in a serious condition.
The rebels, often armed with AK-47 assault rifles, are fighting to create a separate homeland for the tribespeople. They operate out of Bangladesh to carry out their hit-and-run guerrilla strikes in Tripura.
Tripura shares an 540-mile land border with Bangladesh.