Massive Fire under Delhi Metro - Why and How ?

Today Morning Massive Fire caught out under Delhi Metro. 

Why and How - Nobody could confirm properly. Report says - No casualty has been noted as no of Fire Brigade rushed into the Spot and could tackle down the Fire under control. It was the morning at around 5.50 am , so road was clear for the FireBrigade, be it in Office Hours - it could have been a Dangerous Incident. 

Here is the Recording video : https://youtu.be/jOPvgII2Y0U