A child was among the three people taken to hospital after a suspected gas leak at the Hurstville Aquatic Leisure Centre, which is believed to have been sparked by an equipment fault in the spa plant room.
Fire and Rescue NSW crews were called to the centre on King Georges Road just after 10am after reports of a “strong toxic smell”.
Nine people, including at least five children, were treated at the scene after inhaling the fumes.
Three patients – two adults and a child – were taken to St George Hospital in a stable condition.
The centre is currently closed temporarily as firefighters work on ventilating the site.
“The Fire Brigade is currently on-site working with local management and we will reopen as soon as everything has been cleared as safe,” the centre said in a statement.
“When a patient is exposed to any type of chemical there’s always an unknown to the extent of their injury,” NSW Ambulance Inspector David Stride said.
“Incidents like this can happen in a matter of seconds so it’s always important to be aware of your surroundings.”