The accident is described as the worst of its kind in the island nation, according to the police. Two elephants survived and were taken to veterinary care.
Killing or injuring elephants is a crime in Sri Lanka, which has an estimated 7,000 wild elephants. In the wild, they live an average of 60-70 years.
Two elephant calves and their pregnant mother were killed in a similar train accident in the same area in September 2018.
There have been calls for train drivers to slow down and use train tutors to warn animals on the railway tracks. According to local media, around 20 elephants are killed by trains every year.
Elephants, whose natural habitats are affected by deforestation and dwindling resources, have increasingly wandered into areas with human activity.