Fault in tracks was the possible cause of derailment of the Delhi-Kamakhya North East Express in Bihar in which four people were killed and several injured, sources said on Thursday citing a preliminary investigation report.

The report, signed by six railway officials including the driver of the ill-fated train, stated, "It seems that derailment occurred due to fault in tracks." It estimated the cost of damage due to the accident at more than Rs 52 crore.