BEIJING, China (CNN) -- An explosion at a fireworks plant killed 15 people and wounded six others in northern China, state media reported Sunday.

The deadly explosion occurred Saturday at a plant in Sijiazi Township in the Inner Mongolia Autonomous Region, the Xinhua news agency said.

On Sunday, rescue workers found two bodies buried in the rubble, bringing the total to 15, Xinhua said.

The blast may have been set off after workers at the plant did not follow regulations while weighing and mixing ingredients to make fireworks, Xinhua reported