Classes resumed Thursday at McKinley Elementary School in Fairfield after officials say a contractor accidentally put a chemical in the building's hot water supply earlier in the week.

The school was closed Tuesday and Wednesday while the water system was flushed. Interim Superintendent Dr. Stephen Tracy says an independent water company from Stratford took more than 30 water samples and ruled the water safe.

According to Tracy, a contractor on Monday accidentally put a chemical meant for the boiler system into the hot water system. He says the water system was then shut down, causing the school to close for the two days.

Dr. Tracy says the only way someone would have become sick was if if they drank hot water, and health officials say no one has complained about any issues.

Parents met with administrators Thursday night at McKinley to have their concerns addressed. Some of them say they are frustrated by how the school handled the closures. Others defended how the school handled the situation, saying it was almost impossible to predict.

Administrators say they are working on ways to prevent a similar situation.