A speedboat carrying Indian tourists near the popular southern Vietnam destination of Phu Quoc island capsized on Saturday, killing 15 people, according to government officials.

The speedboat was traveling from a nearby island to An Thoi, a port at the southern tip of Phu Quoc, officials said, a region known for its white sand beaches and coastal landscapes.

Around 1 p.m. local time, a “serious waterway traffic accident occurred,” the Vietnamese government said in a statement.

According to a statement from local officials, the boat overturned because of rough seas and strong winds about 400 meters into its journey.

It was operated by a company called Ocean Pearl Island, which could not be reached for comment late Saturday.

The Indian Embassy in Hanoi said in a statement that 15 people — thirteen men and two women, all Indian nationals — had died.

India’s prime minister, Narendra Modi, offered “sincere condolences to the families who lost their loved ones” in a social media post.

The ship had 36 people onboard: 32 Indian tourists, three crew members and a guide, according to officials in Phu Quoc. Twenty-one people were rescued alive, they said in a statement, adding that they would investigate what had happened.

The Indian Embassy said that control rooms had been set up in Hanoi, the capital, and Ho Chi Minh City, in southern Vietnam, for families looking for information.