CHANGSHA, Sept. 23 -- Twelve people were confirmed dead and two more missing after an explosion at a firework plant in central China's Hunan Province on Monday, local authorities said Tuesday

The blast happened at around 3 p.m. Monday at the Nanyang Export Fireworks Factory in Baofeng Village of Liling City when 47 workers were at the scene, the rescue headquarters said.

The blast left 12 workers dead, two more missing and also injured 33 people, including three passersby. Three workers were unhurt.

Four severely injured have been transferred to a better hospital in Zhuzhou City. Twenty-six remained hospitalized in a hospital in Liling and three slightly injured have returned home.

A rescue operation is still under way.

The factory was cordoned off, and surrounding areas were scattered with debris and glass shards from broken windows of nearby village houses.

Liling City is a major production base for China's fireworks, which play a major role in traditional festival celebrations like the Lunar New Year.

The city government said the factory was licensed and the cause of the explosion is under investigation.