A speedboat carrying Indian tourists capsized in southern Vietnam, killing 15 people in an accident that occurred shortly after the boat left an island trip.

According to officials and a witness cited by the Associated Press, the speedboat overturned on Saturday afternoon shortly after departing Hon May Rut Ngoai Island, near Phu Quoc—the country’s largest island. The boat went down less than half a kilometer from shore, and passengers reportedly shouted for help as nearby boats rushed to assist.

The vessel had 32 Indian tourists and four crew members onboard. Twenty-one people were rescued, and authorities said the dead were recovered and the injured were taken to hospitals. A witness described rough seas and said the rescue efforts arrived too late for some passengers, and also noted that emergency medical care was not available at the shore when survivors were brought in.

India’s Lava International confirmed that some of its employees and channel partners were among those involved, saying its priority was to support the affected families.

The accident triggered condolences from India’s Prime Minister Narendra Modi, while Vietnam’s prime minister ordered an investigation and directed authorities to hold those responsible accountable and review maritime safety in the area.