https://www.bbc.co.uk/news/uk-england-60849142Olympic Park: Major gas leak incident at London Aquatics CentreA major incident has been declared and dozens of people are suffering breathing difficulties following a gas leak at the London Aquatics Centre.
About 200 people were evacuated from the centre at the Queen Elizabeth Olympic Park, Stratford, after a large amount of chlorine gas was released.
The park said paramedics were treating "a number of casualties with breathing difficulties".
Residents in the area have been asked to close windows and doors.
The fire service said the gas leak had been caused by a chemical reaction, causing a "high quantity of chlorine gas" to be released.
"While we ventilate the premises we would ask those residents in the immediate vicinity to close doors and windows," said a London Fire Brigade spokeswoman.
The centre was one of the main venues for the London Olympic Games in 2012, and was used for swimming, diving and synchronised swimming. It opened to the public in 2014.
The pool is operated by Greenwich Leisure Limited (GLL), which said the release of gas occurred when "the facilities management company that operates the plant room took delivery of pool chemicals".
"We are working to support all those affected," it said.
"We are awaiting guidance from the facilities management company, London Legacy Development Corporation (LLDC) and the emergency services on when the centre will be able to reopen."
Mayor of London Sadiq Khan said: "Please avoid the area which has been cordoned off and evacuated.
"I remain in close contact with our emergency services who are dealing with a gas-related incident at the London Aquatics Centre this morning," he added.
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At the scene
BBC News correspondent Greg McKenzie
It looks and feels like a major incident - emergency service resources are huge and there is a cordon in place.
There are lots of fire engines and ambulance personnel I can see, and it looks like they've created a makeshift centre to treat those with medical problems.
I am standing about 800m away from the Aquatics Centre, but I have been able to speak with one woman who was there this morning.
She was there for a morning swim and there was quite a few people there with children. They were told there was an issue with chlorine and they had to be evacuated quickly.
As they were leaving, she could see some people struggling to breathe, but she said the evacuation was efficient and emergency services were quick on scene to help.