China's Ministry of Emergency Management announced that some 200 fire and rescue workers had been dispatched to a shoe factory in Fujian province on Thursday.
Authorities have confirmed that there were casualties, but exact numbers have yet to be released. They said an "all-out" effort was underway to put the fire out.
President Xi Jinping was quoted by state media that "heavy human losses" were expected as many workers were believed to still be trapped inside the building in the city of Jinjiang.
"No effort must be spared in search and rescue operations and in supporting the families" he added.
Dozens of fire trucks were seen dumping water on the burnt multi-story factory as smoke continued to billow from the site.
