A firework display at the Hangzhou West Lake Expo. Dong xuming / for china daily

The cause of the accident has not been determined, but a local radio program, Hangzhou Traffic 918, said a malfunction occurred during the lighting of the fireworks, causing them to explode in midair.

One tourist surnamed Ma said that four or five fireworks — instead of blasting into the air — shot straight at her "like bullets" about 15 minutes after the show had begun, Xinhua News Agency' affiliate Xiandai Jinbao reported. The "spray of sparks" continued for around 20 seconds, sending the crowd scrambling for cover and screaming for help, Ma said.

Others complained that security officers at the site were "inexperienced students" from a police school and offered little help. They also said the fireworks continued after sparks began hitting the audience.

A total of 150,000 fireworks have been lit for the expo this year, 50,000 fewer than last year. The smaller number is due to "environmental protection".

Around 30,000 fireworks were lit at the Grand Canal. All of the fireworks were less than 10 centimeters wide.

Residents, especially in the capital city of Zhejiang province, called for a reduction in annual firework displays after the accident, saying it would reduce noise and air pollution.

Statistics from the Hangzhou-based Qianjiang Evening Newspaper showed that 260 tons of garbage were produced and 883 traffic accidents were reported during the one-night firework display on Saturday.

Gu Xiaoming, a sociologist from Fudan University, said a public event should not be canceled or criticized just because an accident had happened.