New Delhi: The October 11 derailment of the 12506 Anand Vihar Terminal-Kamakhya Northeast Superfast Express at Raghunathpur station in Buxar district of Bihar late was possibly caused by a fault in the tracks, PTI reported. This is based on a preliminary investigation report.“It seems that derailment occurred due to fault in tracks,” says the report signed by six railway officials, including the driver of the train that derailed.Four people were killed and more than 60 injured in the derailment. The loco pilot was partially injured and his assistant suffered serious injuries.The preliminary report, according to the agency, contains a statement from the loco pilot, according to which “the train passed Raghunathpur station, near which the accident occurred, at a speed of 128 km per hour, but soon after it crossed the station section it suffered a severe jolt at the rear end with excessive vibration”.“As a result of the excessive vibration and the severe jolt, the brake pipe pressure dropped suddenly and the train derailed at 9:52 pm,” PTI reports.