A crack in the tracks prima facie caused the derailment of eight coaches of Mahakaushal Express near Mahoba station in Uttar Pradesh on Thursday.
Speaking on the sidelines of a function, Minister of State for Railways Manoj Sinha said that "according to the divisional railway manager, prima facie fresh weld failure on left side caused the derailment."
Fresh weld means it was not an old crack and that the crack developed suddenly and could not be detected.
While the UP Additional Director General (Law and Order) Daljit Chaudhary said 52 passengers were injured in the mishap, Sinha said 21 were injured, including one seriously.
The derailment took place near Mahoba station in Uttar Pradesh.
The DRM of Jhansi Division and General Manager of North Central Railway have rushed to the site after the accident to supervise the rescue and relief operations.
Railways have ordered an inquiry into the derailment which left 400 metres of track damaged. The mishap disrupted rail traffic on the route with services of 14 trains disurpted, railway officials said.
In Lucknow, ADG (Law and Order) Daljit Chaudhary said that the incident took place around 2.20 am when eight bogies of the train derailed injuring some 52 people of which two suffered "serious fractures" and have been referred to a Jhansi hospital.
Some have been discharged after first aid while others have been admitted to local hospitals, the ADG said, adding that ambulances and teams of doctors reached the spot and monitored the relief and rescue operations.
Chaudhary said that prima facie there was nothing suspicious but all aspects will be investigated as it is a serious issue.
Railway officials and teams of anti-terrorist squad and and National Disaster Response Force are at the spot and investigations are on to ascertain the cause of the mishap, the ADG said.
Superitendent of Police (Mahoba) Gaurav Singh said the incident took place between Mahoba and Kulpahad railway stations near Supa village.
UP Minister for Health Siddharth Nath Singh, who rushed to the spot, announced a monetary assistance of Rs 50,000 each to the seriously injured and Rs 25,000 to those who suffered minor injuries, the SP said.
Railway Board member (Traffic) Mohd Jamshed said in Delhi that an inquiry into the derailment will be conducted by a senior railway official.
Asked whether it was an act of sabotage or any defect in the rolling stock led to the mishap, he said, "Nothing can be ruled out till the report is submitted."
On some recent cases involving security around rail tracks in different parts of the state, the ADG said investigations proved there was no terror link but all cases are being thoroughly probed with the help of experts.
All coaches that derailed on Thursday were conventional ones and manufactured at the Integral Coach Factory in Chennai. Though a few coaches tumbled, they did not climb over each other as it happens in such cases, resulting in minimum damage.
The train with 10 coaches left the accident site at 6.48 am.
Railways have pressed 15 buses into service for carrying about 200 passengers, who were travelling in affected coaches, to Jhansi.
At least 17 helplines have been made operational at different stations en route to assist relatives of passengers travelling in the train.
Besides, railways have made catering arrangement for the passengers on the site.
The derailment has affected services of 14 trains, out of which seven were diverted and an equal number of trains cancelled.
Jamshed said the line is expected to be restored by midnight as the damaged section of the track has to be replaced.
The Railways has issued following helpline numbers:
Mathura: 0565-2402008 / 2402009
Kanpur: 0512-1072 / 2323015 / 2323016 / 2323018
Allahabad: 0532-1072 / 0532-2408149
Nizamuddin Station (Delhi): 72510 / 72389 / (P&T - 24359748)
New Delhi Railway Station: 22623 / (P&T - 23342954 / 23341074)