Photo: Screenshot of People's Daily video

An investigation has found that the explosion at a firework factory in Guanghan, Southwest China's Sichuan Province on Wednesday night was caused by nitrocotton catching fire.

Experts at the scene said that high temperatures caused the nitrocotton to release and accumulate heat, which then led to self-ignition. This lit charcoal and firing leads stored nearby, triggering the explosion, the publicity department of the Guanghan government said Thursday, Chengdu Economic Daily reported.

Six people were injured in the accident, with four being badly injured. The fire was put out at 4:20 am on Thursday.

The city vowed to save those who had been injured and enforce administration and safety measures. The city will also check the local firework industry.

More than 700 nearby residents were evacuated from the scene, the China News Service reported earlier.

Videos posted by netizens on Sina Weibo on Wednesday night showed a huge fire and the sound of explosions.

Global Times