Thousands of students and migrant workers from the northeastern states of India have fled the southern city of Bangalore amid panic about their safety.
Special train services were organised to meet the demand.
Home Secretary RK Singh blamed the mass exodus on "rumour mongering" and insisted there was was no threat to anyone from the north-east living anywhere in the country.
BBC correspondents say rumours of attacks may be linked to clashes in the state of Assam last month.
More than 300,000 people fled after fighting between Bodo tribes and Muslim settlers there.
Fresh trouble between the two sides was reported on Thursday when a mob burnt down a bus and a bridge.