Chilean officials say about 20 whales have been found beached along the country's southern coast.

The National Fisheries Service said Friday that foreign scientists discovered the whales on the Gulf of Penas and reported them to authorities.

It's not unusual to find beached whales along Chile's 2,400-mile (4,200-kilometer) long coast, but the Fisheries Service says it's the first time sei whales have been found beached. The International Union for Conservation of Natures lists the sei as an endangered species. Adults can be longer than 50 feet (15 meters) and weigh 20 tons or more.

Officials say they are trying to determine what caused the whales to wind up on the beach.