An express train rammed into a stationary train at Kavarapettai in Tamil Nadu and several passengers are feared injured, the police said.
A fire broke out quickly near a coach and only sketchy information is available right now on the accident, the railway police said.
At least two coaches have derailed and rescue teams and ambulances have rushed to the spot, the police added.
When contacted to seek information on the mishap, railway officials did not answer phone calls.
Kavarapettai is near Chennai.