A chemical leak at the Marathon Refinery in Mandan Monday morning forced workers to evacuate. The leak began around 8.

The Department of Environmental Quality says it was gaseous hydroflouric aci– which is used in oil refining and other chemical processes.

While hydrofluoric acid is considered a “weak acid”, it is still dangerous to humans and is capable of irritating and dissolving skin.

Employees were ordered to leave the refinery immediately once the leak was discovered.

In order to seal the released acid, Marathon safety teams used water cannons that blasted the gas- transforming it into a liquid and preventing it from escaping the site.

The department says crews quickly and safely cleared up the acid, and employees were able to return to work mid-morning.

Marathon says there were no injuries, and the cause of the leak is still under investigation.

Both the company and state official have declared that the leak did not pose a risk to the public.