The 3 elephants were hit by the train in central Assam.
Three elephants were killed after they were hit by a speeding train in Assam early Monday, an official said.
The incident took place in the Jogijan area near Hojai railway station in central Assam.
The Dibrugarh-bound Vivek Express sped into a herd trying to cross over to the other side of the track, killing three elephants.
Locals said that the train was travelling at high speed and did not comply with the recent instruction of the Forest Department to slow down during the night while approaching areas frequented by elephants.
However, railway authorities said that the area was not an identified elephant corridor and hence there was no question of any speed limit.
"We have come to know that there was an accident leading to death of three elephants. The area where the incident took place is not an identified elephant corridor. The train was at normal speed, which is 100 km/hr," Northeast Frontier Railway (NFR) Chief Public Relation Officer Pranavjyoti Sarma said.
On September 27, two elephants were killed after they were hit by another speeding train along the Assam-Nagaland border.
Elephant deaths due to train hits have become a regular phenomenon during winter in certain identified elephant corridors in Assam.
NFR officials, however, said that efforts were undertaken to reduce the incidents and that the number of elephants killed by trains have gone down in recent years.
A total of nine elephants were killed in train-related accidents in Assam 2015.
The Union Ministry of Environment and Forest had issued a general advisory for prevention of accidents involving elephants in 2010.
The officials said that there were 27 identified elephant corridors falling under NFR, including two temporary ones, and they have issued clear instructions to the loco-pilots to restrict speed to a maximum of 50 km/hr while crossing these.
They are also supposed to constantly whistle while crossing the identified elephant corridors.