A fireworks factory explosion in Liuyang, Hunan province on Monday has killed 21 people and injured 61 others, state media said.

The explosion occurred at around 4.40 pm in a workshop at the Huasheng Fireworks Manufacturing and Display Company in the county-level city famous for its firework production, under the provincial capital Changsha.

President Xi Jinping has urged all-out efforts to search for people who are still unaccounted for and save the injured.

Online footage circulating on Chinese internet platforms showed thick white smoke rising high into the air from the explosion site.

The explosion also broke doors and windows in the homes of neighbouring villages, where residents reported that heavy rocks were blown on to roadsides in the blast. Some villagers said they had left the village due to safety concerns.