SHANGHAI, Jul 10 -- SHANGHAI'S recent spate of sultry weather has turned into a deadly season for youngsters trying to beat the heat with a cool dip.

Two brothers remained missing yesterday after one floundered in a river in Nanhui District and his older sibling jumped in to try to save him. A few hours earlier in a nearby pond, searchers found the body of an 11-year-old girl who drowned in a separate incident.

The mishaps - each involving children of migrant workers - occurred in a five-meter-deep branch of the Dazhi River in Xinchang Town.

Witnesses to the apparent drowning involving the brothers said a 10-year-old boy was playing along the shore with his 12-year-old sibling about 5pm on Sunday when the younger child took off his clothes and jumped into the river for a swim.

When the boy sank below the surface, his brother jumped in to save him, witnesses said.

Police organized rescue efforts using a fishing net but were unable to find either child. An area resident said the boys were members of a migrant family from Shandong Province.

"Their father works on a construction site nearby," said the resident, surnamed Ye.

Earlier Sunday, the girl slipped into a lotus-filled pool connected to the river - a spot only 200 meters from where the boys went missing. Her lifeless body was found 10 minutes later.

The girl, an only child, was the daughter of a migrant family from Sichuan Province.

Just a week ago, three Sichuan Province girls - two 13-year-olds and the other 10 - were found drowned in a natural pool in Pudong New Area. Witnesses said there are four such pools where children often play and look for crayfish.

A study on child drownings between 2000 and 2005 showed accidents are the top killers of Chinese youngsters. Some 60 percent of all fatal accidents involving children were drownings.

Parents, the government and society need to do a better job addressing the problem by adopting preventative measures and conducting more education, doctors urged, especially during summer, the peak season for drownings.

The Shanghai Education Commission has ordered schools to teach students to swim in safe places and avoid playing in rivers.