Changsha: The fireworks plant explosion in central China's Hunan Province has left 21 people dead and 61 others injured, authorities said Tuesday. 

The explosion occurred at around 4:43 p.m. Monday at the plant of Huasheng fireworks manufacturing and display company in Liuyang, a county-level city under Changsha, capital city of Hunan.

More than 480 rescuers in five teams have been mobilised for the rescue, with three rescue robots deployed.

As the explosion site is located near two black powder warehouses, the rescuers have evacuated nearby residents and set up a buffer zone to prevent a secondary accident.

Recue operations in full swing

As of 8 a.m. Tuesday, the rescuers had confirmed the casualties following the first round of searching. The injured have been rushed to hospital for treatment and the second round of searching is underway.

The Ministry of Emergency Management has dispatched experts to the scene to guide the emergency rescue efforts.

The person in charge of the company has been detained by police and the cause of the accident is being investigated, Xinhua news agency 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".

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

Liuyang city is known for fireworks manufacturing, touted in reports as the world's largest producer of fireworks.

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.