Indian officials say they suspect tribal rebels in the remote northeastern Tripura State have killed 10 people Wednesday. This is the latest in a string of attacks on Bengali settlers in the region.

Indian Police say a group of tribal militants burst into a market at Moharchara village and opened fire with automatic weapons just as people were closing shops late Wednesday.

Tuesday, suspected tribal rebels gunned down at least 21 people, including three children in separate attacks.

All the attacks have targeted Bengali-speaking settlers.

Rebel tribal groups say hundreds of thousands of illegal immigrants from neighboring Bangladesh have moved into the state in recent decades, turning the indigenous tribal population into a minority.

No one has claimed responsibility for the attacks. But police suspect two outlawed rebel groups: the All Tripura Tiger Force and the National Liberation Front of Tripura. Both groups are fighting for a separate homeland for the state's tribal community, which makes up 30 percent of Tripura's population. The rebels complain their identity is threatened by the Bengali settlers in the region.

Tripura Chief Minister Manik Sarkar says the recent attacks were "clearly planned" by the two groups who may be joining forces to push ahead with their demand for a tribal homeland.

Tripura State shares a 856-kilometer unfenced border with Bangladesh.

The federal government says it is making efforts to prevent Bangladeshi nationals from entering India illegally.

Nearly 10,000 people have been killed in the tribal insurgency in Tripura in the past two decades.