Students and staff were evacuated after a chemical spill at a warehouse.
Tolworth Girls' School students were evacuated from their Portacabins after battery acid started leaking from a computer room at CP Lighting, in Tolworth's Red Lion Business Park.
Staff from the lighting firm were also forced to stand outside for four hours while 40 firefighters tackled the leak from 11.05am.
The overpowering fumes smelt like a very strong dose of kettle descaler, according to owner Paul Reading, who told staff to leave the building.
He said: "It was very pungent and it needed someone with a breathing mask to go in and clean up the mess and ventilate the building."
The company, which backs on to Tolworth Girls' School, said the back-up computer system which overheated was only four-weeks old, and cost £3,000 to install.
Mr Reading said: "I'm not very happy about it. We sell lighting so are really, really busy at the moment trying to get orders out."
He said the loss of half a days' trade was in its thousands.
Police, London Ambulance Service and London Fire Brigade all attended the scene.
Do you have pictures from the scene? Send them to lrobertson@london.newsquest.co.uk
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