Emergency services responded to calls about the leak – at the Apollo Bay Aquatic and Leisure Centre, Apollo Bay – just before 11am this morning.
It is understood at least two people have been airlifted to the Alfred Hospital while another is being transported to Geelong Hospital.
The leak is believed to be the result of a mechanical malfunction that saw a chlorine pump expel out the wrong mixture.
The entire centre has been shut down and barriers have been set up around the perimeter.
A Country Fire Authority (CFA) spokesperson said that 21 people were being treated after being exposed to the leak, but most would not be required to go to hospital.
Two young children are believed to be among the patients being treated.
“It appears there were multiple people who were inside the building at the time who will be assessed,” and Ambulance Victoria spokesperson said.
An alert about a “chemical hazard” has been issued for the aquatic centre.
CFA have said there is no current threat to the community but have advised people to avoid the area to keep roads clear for emergency crews.
Hazmat crews are en-route.
Chlorine is an extremely dangerous chemical in its non-diluted form. Inhalation or exposure of highly concentrated sources of chlorine can lead to vomiting, coma, and even death