The four were part of a herd that had been crossing the railway tracks as the train approached late on Saturday, about 110 miles from Guwahati, in the state of Assam. Another elephant was seriously injured.
If locals claims are taken in account, the accident spot was an identified elephant corridor.
The accident also led to derailment of the engine of the train, though no one was injured.
Train services were affected in the area as the carcasses of the elephants had not yet been removed. "But the train collided with a few baby elephants surrounded by several adult elephants", the NF Railway CPRO said. Train accidents, poisoning by farmers and electrocution are the main causes of elephant deaths, say forest department officials.
Due to large scale deforestation, elephants have lost their natural habitats and have been forced to come out in plain areas in search of foods.
Though, state forest department has developed a mechanism to monitor the movement of elephant herds besides setting up an anti-depredation squads to protect the elephants from such disaster, it is yet to work effectively.
According to the 2011 census, there are 5,620 wild elephants in Assam, the highest in the country.
The Asian elephants of Assam have been declared as "endangered" by the International Union for Conservation of Nature.