SHANGHAI, July 30 -- AUTHORITIES in Shanghai's Jinshan District had to limit the number of swimmers at an artificial beach as about 50,000 people rushed to the site over the weekend, Youth Daily reported today.

If swimmers surpass 3,000, other visitors were told to stay on the beach for safety reasons. The beach authority also suggested people swim for two hours at the most, Jiang Yonghua, the vice director of the beach management office, told Youth Daily.

Shanghai is in the midst of a heat wave. The temperature climbed to 39.6 degrees Celsius yesterday, the equal hottest day in the city in 63 years.

The temperature is a little bit lower at the Jinshan beach and it proved popular with youngsters. During the peak hours on the weekend, the number of visitors has reached 35,000. However, the swimming area is only 12,000 square meters.

Neighboring lawns and streets were also used as parking space because of the surge in visitors, the newspaper reported.

Many beachgoers didn't obey the rules, causing safety concerns and at least one tragedy thus far, the newspaper said.

One child drowned a few days ago after swimming beyond the safety net and into the deep-water zone, Jiang said in the report.

Though the swimming area closes at 7pm and the beach at 10pm daily, people were found walking on the beach or even swimming at 3am, Jiang told the newspaper.

The beach authority has increased the number of life guards from 32 to 42 and security guards from 40 to 50 to cope with the increased crowds. Each guest will also receive a safety notice at the entrances to the beach, the newspaper said.

Three doctors were at the beach on weekends.

"We have heat stroke patients almost every day," one of the doctors told Youth Daily.