Five elephants, part of a herd crossing railroad tracks in the Rambha forest area of east India, were killed when a passenger train plowed into them.
RN Mohapatra, a railways spokesman, said the incident happened early on Sunday.
The Howrah-Chennai Coromandel Express train was traveling in the Rambha forest area, approximately 180km (110 miles) south of Bhubaneshwar, the capital of the state of Orissa, and about 45 km (28 miles) from Berhampur, when it encountered the herd crossing the tracks.
Forest officials say that the accident could have resulted from poor visibility caused by foggy conditions in the area.
The train was damaged in the accident and rail services in the area were delayed for around seven hours.
Chief conservator of the state's wildlife department, JD Sharma, has accused the railroad authorities of ignoring his department's warnings that trains should slow down, due to a herd of elephants moving in the area. However, Mohapatra said that the warning came too late.
In recent years, dozens of elephants have been killed after being struck by trains when crossing railroad tracks, which often run through national parks and forests. The wild elephant population in India was recently estimated to be only around 26,000.