The bodies of three children were found in a hole at an excavation site in Quang Nam Province Sunday morning.
Two of the children were a 13-year-old brother and eight-year-old sister, while the other was their 10-year-old cousin.
They were found in a man-made hole nearly three meters deep near Tra Cai mountain.
Local residents said the three children went to the area after school to bathe in the stream. They didn't return that night.
A student drowned in the area last year, locals said.
It is still not known who is responsible for the hole. Police are investigating the case.