Sepoy Kamal Dev Vaidya was on operational duty in Krishna Ghati sector on Friday.
The explosives were unearthed during combing operations carried out in the forest.
This is the sixth such incident when IEDs planted by Maoists have blown up killing or critically injuring villagers or policemen engaged in anti-Maoist operations in the jungles here
The fire started in a forest across the LoC and spread to the Indian side in Mendhar sector, officials said.
Over 20 security personnel were onboard the bus, he added.