SHIJIAZHUANG, May 24 -- Five adolescents drowned in a river in north China's Hebei province on Saturday, the local government said on Sunday.

The five children, who were aged between 12 and 14, swam in an unsafe section of a river in Daming county, according to the county government.

Local villagers said the children had gone swimming after a birthday party.

The last body was retrieved at 9:30 a.m. Sunday after 150 people were mobilized into the search.

Drowning cases are known to increase in the summer months, especially in rural regions where rivers and pools are unpatrolled and children are often allowed to play unattended.

A report submitted to China's top legislature last year said drowning and traffic accidents were the biggest causes of accidental death of children.

In April, the Ministry of Education urged its local representatives and schools to strengthen safety procedures, including the installation of warning signs and fences near water.