Paramedics took 29 people to hospital from the London Aquatics Centre in Stratford after a “high quantity of chlorine gas was released” due to a chemical reaction.
Dozens of people were treated by London Ambulance Service for breathing difficulties on the Queen Elizabeth Olympic Park in Stratford.
A total of 48 people were checked over after more than 200 people were evacuated from the swimming facility.
The gas release occurred when the facilities management company that operates the plant room took a delivery of pool chemicals, according to GLL, which operates the London Aquatics Centre.
People were evacuated from the swimming venue and the surrounding area cordoned off.
A GLL spokesperson said: “The emergency services were called and some of our customers have required medical treatment due to breathing difficulties. We are working to support all those affected.
“We are awaiting guidance from the facilities management company, LLDC and the emergency services on when the Centre will be able to reopen.”
Darren Farmer, London Ambulance Service gold commander, said: “This morning we responded to a major incident at the London Aquatic Centre in Stratford, alongside colleagues from the London Fire Brigade and Metropolitan Police.
“We sent a significant number of resources including 13 ambulance crews, advanced paramedics, two medics in fast response cars, two incident response officers, a medical incident adviser and members of our hazardous area response team (HART).
“We also dispatched medics from London’s Air Ambulance.
“Our crews took 29 patients to hospital and assessed a further 48 patients at the scene. The majority of patients were reporting minor breathing difficulties.
“Thank you to all our teams who responded today, both at the scene and in our control room, and to our firefighter and police colleagues.”
LAS said it stood down its response shortly after 3pm.
The London Fire Brigade said the incident happened when a “high quantity of chlorine gas was released”.
“While we ventilate the premises we would ask those residents in the immediate vicinity to close doors and windows,” a spokesperson for the Brigade said earlier.
Fire crews from Stratford and surrounding fire stations were at the scene.
Pictures from the scene showed a large number of ambulances and three fire engines outside the sealed off building being supported by police. Footage filmed from helicopter showed paramedics treating people in the car park outside.
One person was treated on a paramedic’s gurney while multiple swimmers, still in their trunks and goggles, were seen being cared wrapped in foil blankets to keep them warm.
Workers nearby told how they heard a fire alarm going off at around 9.45am with people fleeing the Stratford venue covering their mouths.
A builder told The Standard he saw a group of children emerge from the Olympic swimming pool and around eight elderly people being covered in foil blankets by paramedics.
He said: “The children looked ok but the group of elderly people looked worse off.
Another passerby said he could “sense a strong smell of chlorine” as he jogged past the venue in Stratford.
Shaun Coltress from the London Fire Brigade told reporters at the scene: “It’s my understanding that the centre was open at the time of the call.
“On arrival there had been a large quantity of chemical reaction that had caused chlorine gas to form.
“There was a multi-agency response from police, ambulance and fire service attending worked people working in the building to ensure the evacuation process was robust.”
The Mayor of London Sadiq Khan said he was “in close contact with our emergency services who are dealing with a gas-related incident at the London Aquatics Centre this morning”.
“A number of people are being treated by London Ambulance Service. Please avoid the area which has been cordoned off and evacuated,” he said.
I remain in close contact with our emergency services who are dealing with a gas-related incident at the London Aquatics Centre this morning.
— Mayor of London, Sadiq Khan (@MayorofLondon) March 23, 2022
A number of people are being treated by London Ambulance Service. Please avoid the area which has been cordoned off and evacuated. https://t.co/abRqOK0p2b
The Metropolitan Police said officers were on the scene following a “leak of noxious fumes”.
In a statement, the force said: “Officers were alerted by London Fire Brigade at 9.53am to a leak of noxious fumes at the Aquatics Centre, Queen Elizabeth Park.
“Officers and London Ambulance Service have also attended the scene. A number of people have been evacuated from the premises.”
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.
