The father, his wife - both thought to be in their 40s - and their young son, aged around 12, were treated at the scene by South Central Ambulance Service for gas inhalation and taken to hospital as a precaution. No-one was seriously injured.
Firefighters used breathing apparatus to enter the plant room. They used dry earth to soak up a small amount of spilled chemical and ventilated the room. Crews from St Mary's, Redbridge and Hightown dealt with the incident.
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The families of two severely disabled men injured at the same care home say they're still trying to find out what happened two years on.
Forecast for tonight and tomorrow in east of region
Forecast for tonight and tomorrow in west of region