London firefighters dealt with a chemical incident at a factory on Cray Road in Sidcup.
There was a leak of hydrochloric acid at the plant. It was isolated at around 2330.
Firefighters remained at the scene throughout the night taking readings of chemicals in the air.
Around 200 people evacuated the building before the Brigade arrived. There are no reports of any injuries.
The Brigade was called at 2039 and the incident was handed over to onsite management at 0526.