New Delhi (CNN) -- Indian authorities called for calm Friday after panicked people from northeastern India fled cities across the country in fear of retaliatory attacks.
Students and workers from the northeastern state of Assam say they received text messages threatening retribution for ethnic violence that has gripped their state in recent weeks.
The texts prompted as many as 7,000 people to flee cities, including Mumbai, Pune, Hyderabad, Pune and Bangalore, India's technology hub.
Indian authorities banned mass text messages Friday, the Home Ministry said. For the next 15 days, Indians can no longer send more than five texts at a time.
Prime Minister Manmohan Singh told parliament that he did not want to assign blame but the rumors were an attack on India's unity and integrity.
"I would urge this house to send a message loud and clear to all the people of the northeast residing in different parts of the country that our people are one, that we will do everything to provide security to the people of the northeast residing in various parts of the country," Singh said.
Assam's latest episode of violence erupted after two Muslim boys were shot July 19 by members of the indigenous Bodo tribe, according to J.N. Choudhury, the state's director general of police.
Muslims retaliated by killing four Bodos. That triggered widespread rioting.
Since then, police say at least 80 people have died and more than 300,000 people have been displaced.
The Bodos are Bengali tribals from Bangladesh who migrated to India decades ago; many were brought by the British as laborers.
Now, the Bodos fear being marginalized by the increasing number of Muslims, who have much more recently crossed the border illegally from Bangladesh, and would like to carve out a state of their own in Assam.
CNN's Moni Basu contributed to this report.