The Trivandrum Mail derailed outside Chennai close to the Pattabiram railway station. (Representational Image)
All train services to and from Chennai remain suspended after two coaches of the Trivandrum bound Trivandrum Mail derailed outside Chennai at the Pattabiram railway station.
The derailed coaches, according to railway authorities, also collided on the side of another local train, running in the same direction on the adjoining railway track.
"It's a side collision," said a senior officer.
Seven people suffered injuries. They are being treated at a nearby military hospital.
Three National Disaster Response Force teams comprising 135 personnel and two doctors have been rushed to the derailment site.
Authorities say it may take around four hours to resume services on all four lines.