City fire chief Du Zhenzhou told state media his personnel struggled to reach the upper levels of the building because stairwells and exits were blocked with shoe materials.
He said adhesives and other raw materials used in making shoes had fuelled the fire.
The blaze was being extinguished, the emergency management ministry said, demanding “all-out” efforts to put it out, search for trapped survivors and treat the injured.
Some people were trapped and “out of contact”, Xinhua said.
A total of 237 workers and two delivery people were at the factory at the time of the blaze, CCTV reported, adding that 213 people had been evacuated, but it was not immediately clear how those figures squared with the death toll.
Xi said there had been “several major industrial safety accidents” in China so far this year.
“All regions and relevant departments must draw profound lessons from these incidents,” he said, adding that they should “implement rigorous and effective safety measures”.
China launched a campaign against fire hazards in high-rise buildings in November, after a huge blaze engulfed several tower blocks in Hong Kong, killing 168 people.
A month later, a fire at a residential building in southern China’s Guangdong province killed 12 people.
In May, a blast at a fireworks factory in central China killed 37 people, marking one of the nation’s deadliest industrial accidents in years.
