ASHEVILLE, N.C. (WGHP) — Three people were taken to a hospital after an incident possibly involving chemicals in a North Carolina pool, according to WLOS.

At about 1:40 p.m. Saturday, the Asheville Fire Department responded to a “possible hazardous materials incident” at a pool at the Asheville Racquet Club on Resort Drive in Asheville.

The fire department told WLOS that the people reported having “difficulty breathing and difficulty speaking between breaths.”

Eight people were impacted, and one adult and two children were taken to a hospital for additional evaluation.

While the fire department was unable to confirm the cause of the reaction to WLSO, the department said believe the reaction may be related to muriatic acid—also known as hydrochloric acid—and chlorine.

You may know chlorine as a chemical commonly used to kill germs in water, according to the CDC.

Muriatic acid, similarly, is “a component of commercial chemicals used to clean and disinfect swimming pools.

Despite their common usage in pools, both chemicals can be dangerous if inhaled and the quantity of these chemicals in pools is usually carefully monitored.

“Hydrogen chloride vapor is heavier than air and may cause asphyxiation in enclosed, poorly ventilated, or low-lying areas,” the CDC says. Inhalation of hydrogen chloride can lead to pulmonary edema, and ingestion can cause severe injury to the mouth, throat, esophagus and stomach.

The CDC says symptoms of chlorine exposure include blurred vision, coughing, chest tightness, difficulty breathing, a burning sensation in the nose, throat and eyes, and burning pain, redness and blisters on the skin. To see a full list of symptoms, visit the CDC website.

The CDC also has a guide on how to safely use chemicals in swimming pools.