Four elephants, including two calves, were killed by lightning in northern Sri Lanka in one of the worst wildlife tragedies to hit the country in years, officials said Sunday.

A female elephant, aged about 25 years, and two of her calves, aged 10 months and two years, and an eight-year-old female were found dead Sunday just outside the Wilpattu wildlife sanctuary, an official said.

"Villagers from neighbouring areas alerted the authorities and we carried out autopsies," wildlife veterinary surgeon Chandana Jayasinghe said. "The deaths were caused by lightning."

Local villagers in Mahavilachchiya, 250 kilometres (156 miles) north of Colombo, had reported heavy rains accompanied by thunder and lightning in the shrub jungle area on Friday when the elephants were thought to have been struck.

It was the worst natural disaster involving elephants since February 2011 when four baby elephants drowned in a major flood in the north-east of the country.

Elephants are venerated in the mainly Buddhist country and they are a highly protected species. Elephant deaths must be investigated and death certificates issued before disposing of the carcasses.

Despite tough conservation laws and the elephant's association with Buddhism, nearly 200 jumbos are killed each year by villagers after accidentally straying onto farmland, while the animals themselves kill about 50 people each year.

Sri Lanka's elephant population has reduced to just over 7,000, according to a census five years ago, down from a population of over 12,000 at the start of the 20th century.