A blast at a southern China fireworks factory killed at least 11 people and injured 17 on Friday.

Bloodstains are seen on a collapsed concrete pillar among the rubble.

Chinese state television quoted a local administrator of work safety, saying that the explosion was caused during machine maintenance, when sparks ignited raw materials and semi-finished fireworks.

The 17 injured were receiving treatment in hospital, while the factory manager was in police custody Saturday.

An investigation is underway.