Firefighters were called to a smell of chemicals at a health club in the financial district of Canary Wharf in London, triggering the evacuation of 900 people.
A mix of chemicals caused high levels of fumes and vapour in the Credit Suisse building in Cabot Square, the London fire brigade (LFB) said.
The health club in the building is run by Nuffield Health. The company has directed queries to Credit Suisse, which has been approached for comment.
Dave Hill, an LFB station commander who was at the scene, said: “Crews have carried out a sweep of the building and found elevated readings.
“Firefighters have ventilated the building and are monitoring the levels of fumes. We have evacuated around 900 people from the building as a precaution.”
The brigade was called at 9am and the incident was over by 12.30pm with people allowed back in the building and road cordons lifted.
Two fire engines from Millwall and Poplar stations and two fire rescue units from Bethnal Green and Euston were called to the scene.
The incident comes two weeks after 29 people were taken to hospital when a high quantity of chlorine gas was released in an accident at the aquatics centre at London’s Olympic park.
Some of the injured included swimmers in a parent and toddler group who were in the children’s pool at the time of the incident.
About 200 people were evacuated from the centre. At least nine construction workers on a neighbouring site were also treated at the scene.