The explosion occurred at around 4.43pm on Monday at the Liuyang Huasheng Fireworks Manufacturing and Display Company in Liuyang, Hunan province, state broadcaster CCTV reported.
Following the blast, all fireworks makers in Hunan’s provincial capital Changsha, which administers Liuyang, had been ordered to stop production ahead of safety inspections, CCTV said.
Videos on social media from Monday showed continuous explosions accompanied by a vast cloud of smoke rising high into the air in a rural area surrounded by mountains.
Drone footage from CCTV taken a day later showed a swathe of smouldering debris where buildings had stood, with rescue workers and excavators scouring the rubble.
Smoke continued to rise from some buildings left standing, many of them with their roofs blown off.
Changsha mayor Chen Bozhang told a news conference this afternoon that another five people had died since earlier reports that 21 were killed.
“We feel deeply grieved and filled with remorse,” Chen said, adding that search and rescue work was “basically complete”.
The central government had sent experts to guide rescue efforts, while more than 480 rescuers had been urgently dispatched to the site, according to CCTV.
They had established a 3km control zone around the site and evacuated people nearby.
Police had apprehended the company’s management while investigations into the cause of the accident continue, CCTV said.
President Xi Jinping had called for “all-out efforts” to treat the injured, search for missing persons, and for those responsible to be held accountable, state news agency Xinhua reported.
Liuyang is a major fireworks hub, producing around 60% of the fireworks sold in China and 70% of those exported.
Industrial accidents, including in the fireworks industry, are common in China due to lax safety standards.
Last year, an explosion at another fireworks factory in Hunan killed nine people, and in 2023, three people were killed after blasts struck residential buildings in the northern city of Tianjin.
In February, separate explosions at fireworks shops in Hubei and Jiangsu provinces killed 12 and eight people.