The cause of the blast, which took place at around 6:40 a.m.
Local news reports said that when the explosion took place, people had been buying and selling produce and eating breakfast at the market, which is in a residential area in the city’s Zhangwan District.
The governor of Hubei, Wang Zhonglin, rushed to Shiyan to direct rescue efforts, the authorities said.
Taking stock of “hidden dangers” and being on the lookout for major emergencies would help create a “favorable atmosphere,” Mr. Xi said, ahead of the July 1 centenary of the Chinese Communist Party’s founding.
In recent years, deadly blasts in industrial zones have led the Chinese authorities to become stricter about enforcing safety rules.