Four people, including a Maricopa firefighter, were transported to hospitals after a chlorine leak at an indoor swimming pool at Province Community Recreation Center prompted a hazmat response from the Fire and Medical Department on Wednesday morning.

The firefighter was treated and released. The three others who were transported are listed in stable condition.

In all, 11 people were treated near the pool, in the 20900 block of Province Parkway, after a call at about 10 a.m. that several people there were having difficulty breathing.

Upon arrival at the pool, firefighters noticed a distinct chlorine smell and upgraded the call to a hazardous-materials situation, according to city public information officer Monica Williams. Multiple agencies responded, including a Chandler Fire Department hazmat team.

Crews identified the cause of the odor as a chlorine leak originating at the center’s indoor pool.

The investigation into the incident is ongoing.