Five persons were injured in an accidental explosion on a suburban train at central Mumbai's Sion station this afternoon, police said.A gas bottle carried by one of the passengers exploded inside a CST-bound local train standing on platform number two of Sion station at around 12.55 pm, they said.The nature of the gas in the bottle was not immediately known, railway sources said.The injured have been identified as Shahabuddin Ansari (20), Neelesh Patil (28), Santosh Shinde (32), Layak Nasimullah (28) and Paresh Mhatre (27).There was a similar explosion at harbour line's Cotton Green station a few weeks ago in which two persons were injured.