HANOI, May 21 (Xinhua) -- Four students from Vietnam's Khanh Hoa province drowned when taking a bath in a local river, Vietnam News Agency reported on Tuesday.

Two sisters, who were in the sixth and eighth grade, and another girl and a boy in the seventh grade, all students of To Hien Thanh junior high school in Ninh Hoa town, were having a bath in Cai River on Monday afternoon when they slid into a deep hole in the river.

By Monday evening, all the four bodies were found by local residents.

"Drowning is a silent epidemic claiming more than 2,000 children's lives per year in Vietnam," an official from the World Health Organization in Vietnam told Xinhua recently, adding that the rate of child drowning in Vietnam is higher than other Southeast Asian nations and 10 times higher than that of developed countries.

The official said that many deaths caused by drowning in Vietnam were preventable, and the drowning rate among local children would fall if adults supervise kids' activities more closely, and more kids were provided with survival swimming and water safety skills.