The cause was never established, but was blamed on track alignment and faulty wheels, possibly compounded by a failure to notify maintenance workers about the approach of a delayed train that had been making-up time by travelling at excessive speed.

The accident occurred at Peruman bridge over Ashtamudi Lake, Perinadu, Kollam, Kerala, at around 13:15 local time.

Ten carriages of the Train Number:26 Island Express, travelling from Bangalore to Thiruvananthapuram Central, derailed and fell into the lake.

Of the 14 coaches, only the engine, the parcel van and a second class compartment had crossed the bridge when the derailment occurred.

A second inquiry, prompted by public outrage, revealed that problems in track alignment and faulty wheels of coaches were responsible for the tragedy.