More than a thousand liters of toxic chemicals, which leaked out of a damaged barrel of sulfuric acid, caused the German city of Hamburg to be wrapped in thick smog.

The toxic spill occurred after a forklift truck damaged a 1000 liter barrel of sulfuric acid, resulting in more than half of the barrel’s contents escaping into the environment, Ukrinform reports. The sulfuric acid mixed with nitric acid from a container which had fallen off a shelf during the accident, forming a thick cloud of smoke. The cloud, estimated to be several hundreds of meters in diameter, descended upon the city of Hamburg.

Residents of the nearby areas are recommended to stay indoors and keep their windows closed. Firefighters are currently at the accident site.