Prime Minister Manmohar Singh of India has appealed for calm following a panicked exodus from several southern cities of migrants from north-east India.
The exodus began from Bangalore and has spread to the cities of Chennai (Madras) and Pune as well.
Mr Singh said peace "must be maintained at any cost".
The BBC reports officials have blamed the exodus on "rumour mongering" linked to clashes in the north-eastern Assam state.
More than 300,000 people fled after fighting between Bodo tribes and Muslim settlers in Assam.
Fresh trouble between the two sides was reported on Thursday when a mob set fire to a bus and a road bridge.
The main railway station in Bangalore was flooded with migrant workers from north-eastern states for a second successive day on Thursday when three special trains left for the north-east.
A senior Bangalore official told the BBC that nearly 15,000 people from the region had left the city since Wednesday, when the rumours began.
An estimated 250,000 people from the north-east live and work in Bangalore, which is often referred to as the Silicon Valley of India. Many of them are students, security guards and workers in the hospitality sector.