Twelve coaches of Thiruvananthapuram-Mangalore express derailed near Karukutty station, around 45 kms from Kochi, in the wee hours of Sunday, the Southern Railway said.
No casualties were reported in the incident.
After leaving from Thiruvanathapuram at 8.40 pm on Saturday, the 16347 express train derailed between Aluva and Karukutty stations in Ernakulam district at around 2.30 am, a Southern Railway spokesperson said.
Following the incident, buses and local trains were arranged to ferry the stranded passengers to Kochi and Thrissur.
Traffic on both the lines of the route is affected due to the derailment and six to 10 hours are expected to complete the repair works of the damaged tracks on Ernakulam-Thrissur route, he said.
Some local trains connecting major stations of Kerala have been cancelled because of the derailment.