NANCHANG, May 2  -- Three teenagers drowned while swimming in a reservoir in Yichun city in east China's Jiangxi Province Saturday afternoon, the local government confirmed.

The three boys, all ninth graders at Hepu School in Xinfang town in Yichun's Yuanzhou district, were swimming with nine other schoolmates in the reservoir, where swimming is banned, an official in Xinfang town said.

He said one of them was drowning and four others went to his rescue. "But the students knew little about underwater rescue and all five ended up in danger," the official said on condition of anonymity.

A group of fishermen joined the rescue, but only two students were saved in time, he said.

Police have launched an investigation.

Drowning of children has been reported in many Chinese provinces in the early summer.

On the eve of the May Day holiday, Ministry of Education urged schools and local educational authorities to tighten safety management to prevent children from drowning.

The ministry said in a statement that local authorities should clear risks around major water bodies, put up warning signs or cordon off waters that were off-limits to swimmers.