Two cousins reportedly drowned in the Lam River on Sunday afternoon, an official in the central province of Nghe An said, noting that the incident was the eighth since early this month.
The two boys, 8 and 5, were taking a bath by the river near their house when they slipped and fell into a deep part of the river.
Local authorities discovered their bodies the same evening.
Since May 1, there have been eight drowning accidents in the province, involving 14 children. Most of the cases occurred during weekends, when the children were trying to cool off in rivers and ponds, officials said.
Earlier on Saturday, five primary students drowned in two separate accidents in the province.
Three boys, including two twins, went to the beach in Quynh Luu District and never came back. Two others died in a pond near their houses in the town of Vinh.
According to WHO, nearly 6,400 people drown in the country every year and most of them are children.