Workers at a St. George, Utah, apartment complex were sent to the hospital after mixing incompatible pool chemicals.

The incident occurred on September 17 at the Cedar Flats Apartments when two staff members were doing maintenance on the pool.

St. George Fire Deputy Chief Brad Esplin said a mixture of chemicals resulted in a toxic chlorine gas that prompted the evacuation of two nearby buildings.

“We were dispatched around 9 o’clock to reports of a hazmat incident, and when we arrived on the scene, there were two people who were exposed to chlorine gas,” Esplin said. “Acid and chlorine were mixed accidentally in the pool house near the pump room, which resulted in a very toxic chlorine gas.”

The workers were taken to the hospital via ambulance while fire crews cleaned the scene by placing the barrel containing the chemicals into the pool to neutralize the gas.

“What’s nice about being near a swimming pool, which is a large, contained body of water, is we can put it into the swimming pool, which will dilute and contain it,” Esplin said. “We then talked to the maintenance crew, and they balanced the pool chemicals after we added the mixture into it.”