A blast at a fireworks factory in China's Hunan province has killed 21 people and left 61 wounded, according to state media.

The explosion at the Huasheng Fireworks plant occurred at around 16:40 local time (08:40 GMT) on Monday in the city of Liuyang, prompting rescuers to evacuate everyone within a 3km (1.9mi) radius of the plant.

Authorities deployed nearly 500 personnel to conduct search and rescue operations and treat the injured, while robots were used to help find those trapped within the building.

Police, who are investigating the cause of the blast, have taken "control measures" against the person in charge of the fireworks company, Chinese state media reported.

Authorities said that two gunpowder warehouses within the factory area posed a high risk amid rescue efforts, state media reported.

Rescue teams had to evacuate everyone within a 3km (1.9mi) radius of the fireworks plant. They also implemented measures like humidifying the area to "prevent secondary accidents during the rescue".

The blast was so destructive that windows in a residential building near the factory were also shattered, a CCTV reporter noted in a televised broadcast from the scene.

The ages of the injured range from their 20s to 60s, and some suffered bone injuries after being hit by flying debris, said the CCTV report.

President Xi Jinping has urged all-out efforts to search for those still unaccounted for and to save the injured. Xi also called for an investigation into the accident to hold those responsible to account, state media reported.

Speaking to Beijing News, a resident who lives about 1km away from the factory said villagers now have to take detours after stones were blasted onto the road.

"The glass windows in our homes were shattered, aluminum window frames were deformed, and even the stainless-steel doors were twisted out of shape," she said.

Another resident told the news outlet that she has left the village out of fear.

Liuyang city is known for fireworks manufacturing, with reports citing it as the world's largest producer.

Blasts at fireworks factories and shops are not uncommon in China - and are often deadly. In February, 12 people were killed in an explosion at a fireworks store in Hubei province.