Twenty five people have been killed in a day of violence in the north-east Indian state of Assam, police say.
Assamese train passengers were targeted by the Bihar mobs last week
Four women were killed and three others injured when gunmen on motorcycles opened fire in Bongaigaon district.
In the worst incident, six members of a family, all from Bihar state, were hacked to death in Dibrugarh district.
Violence between Assamese and Hindi speaking people has been rising since Indian Railways began a controversial recruitment campaign in Assam.
More than 100 houses belonging to the settlers have been burnt down.
Indian army troops have now been deployed in parts of the state to control the violence.
The chief minister of Assam Tarun Gogoi has spoken to Delhi to send some additional security forces to tackle the situation.
A substantial number of Assam's security forces have been taken out to other states for election duty.
Mr Gogoi has cancelled his engagements for Thursday.
He told the BBC that the rebels belonging to the United Liberation Front of Assam (ULFA) were trying to come back riding on this issue.
The ULFA has told Hindi speakers to leave the state.
In the latest incident, three Hindi-speaking people from the states of Bihar and Rajasthan were gunned down near a cinema hall in Nalbari district.
One more person was injured in the same incident.
A Bengali woman has also become a victim in the clashes between the Assamese residents and Hindi speaking settlers.
She was one of the four women who were shot and killed in Bongaigaon earlier.
Late on Tuesday, five Biharis were shot dead in the western district of Dhubri late on Tuesday.
"All the five killed in Dhubri district were
Hindi-speaking truck drivers who were... watching the India-Australia cricket finals on television," Khagen Sarma, Assam's inspector general of police, was quoted as saying by the Associated Press.
It is not clear who carried out either attack.
The rebels are angered by attacks last week in Bihar on train passengers from Assam by Biharis protesting at alleged job discrimination in Assam.
The Bihar mobs were angry that youths in Assam had physically prevented candidates from Bihar from taking recruitment interviews for jobs at the state-run railways.
Assamese people say the jobs should be reserved for them.