A chemical alert disrupted thousands of shoppers after a bleach and water solution was thrown out of a hotel window on London's Oxford Street.
Seven people were hit by the liquid, thought to have been thrown from the Radisson Edwardian Hotel by a cleaner.
After a woman complained of skin irritation, 10 fire engines were sent to the scene at 1813 BST and officers in chemical suits moved in.
Police closed the street and held shoppers inside department stores.
The road was closed for more than an hour and led to heavy disruption for traffic in nearby streets.
A police spokesman said: "It was a combination of bleach and water.
"It was probably a cleaner who threw it out of the window."
He said the road was closed while the substance was tested.
None of the pedestrians required hospital treatment.
A London Fire Brigade spokeswoman said: "We were called at 1813 BST.
"We sent 10 appliances, which shows the level of the response.
"The incident was over by 1936 BST."