The train

'Here is the sound of bell' this where the last word of the the driver of the train. After speaking the words, driver lost his life due to which the further informations of the train  was not available. So to gather the informations IT department has to do very hard working on it. They were not able to find very large information about it, but they were having the last words of driver. So they started to do investigate on the last wordings they found that somebody has attacked on the train.

Investigated

Driver has switched the button and has lost his life.Driver was not able to understand so he lost both his job and life.But onthat day driver was off duty.So the conclusion was not made.Only thing that came out was driver only was not the culprit.