Hotel guests were overcome by fumes in the spa area and some required ventilation, say firefighters.
Toxic fumes have left 24 people in hospital after a mix of chemicals at a hotel spa.
Hampshire & Isle of Wight Fire Rescue Service was called to the Solent Hotel & Spa, Whiteley, to deal with the “large-scale” incident at 20:44 BST on Monday.
It said chlorine – a poisonous gas – had been created on site when two chemicals were accidentally mixed.
Some guests required ventilation after breathing in the resulting fumes.
Breathing apparatus was supplied by a Hazardous Area Response Team from South Central Ambulance Service (SCAS), which was also at the scene in Rookery Avenue in Whiteley.
It said those taken to hospital included children.
A fire service spokeswoman said: “A number of hotel guests had been overcome by fumes in the spa area after two chemicals had accidentally been mixed together and created chlorine gas.
“Hampshire and Isle of Wight Fire and Rescue Service began immediate emergency care, set up a casualty handling area and requested the ambulance service to attend.
“A ventilation fan was used to clear the fumes and firefighters took the vessel containing chemicals to fresh air. Gas monitors were used to check that the scene was safe.
“In total, 24 people were taken to hospital by ambulance crews.”
Station manager Dave Graham called it a “large-scale incident with multiple people requiring medical treatment for the inhalation of gas”.
He said the scene “was made safe” and was now being dealt by the hotel management.
Firefighters from Hightown, Fareham, Cosham, Portchester, St Mary’s and Romsey were sent to the hotel during the operation.
In a statement, SCAS said eight ambulance crews joined its hazardous response team at the scene.
It added: “Twenty-four patients, ranging from children to those in their 50s, were assessed and treated by our ambulance teams for breathing difficulties.
“Following treatment at the scene by our crews those patients were taken to University Hospital Southampton for further assessment for those non-life threatening injuries.”
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