A major explosion was reported at a chemical plant in the south-central Chinese city of Lengshuijiang Saturday, according to tweets reportedly sent from the scene. It was unclear if anyone was injured or killed, but rescue efforts appeared to be ongoing by noon EST.

The cause of the blast is still unknown, Huang Zhaouyun tweeted. A video said to be of the explosion was uploaded to Youtube and circulated on social media.

The video shows a fire in the background with smoke piling into the sky. About 12 seconds into the 30-second video what appears to be an explosion could be seen and heard.

This is a developing story.