NIAGARA FALLS – Staff and students were evacuated at about 9:30 a.m. Monday from Gaskill Preparatory School after two school employees mixing chemicals in the basement pool area set off a noxious reaction, according to the Fire Department.

The two maintenance workers, who were not named, were taken to Niagara Falls Memorial Medical Center for evaluation, fire officials said.

Students in classrooms were not exposed to the leak, according to fire and school officials. The children were taken to Hyde Park Elementary School as firefighters addressed the situation.

Fire Chief Thomas Colangelo said a maintenance worker accidentally poured a one-gallon container of muriatic acid into 20 gallons of liquid chlorine in a 50-gallon drum that feeds the pool chlorination system at the school at 910 Hyde Park Blvd.

The mixture created a cloud of chlorine gas in the basement area of the school.

In addition to city firefighters, mutual aid was given by the Niagara Falls Air Reserve Station Fire Department’s HazMat unit to help contain the leak, which appeared to be confined to the basement.

Colangelo said crews in full turnout gear assessed the chemical levels in the basement and set up smoke ejectors to ventilate the affected area. Meters were used to assess air-safety levels.

Chiefs on the scene made a decision to route the mixture from the 50-gallon drum through the filter and into the pool to be diluted. Colangelo said that in order to speed up the process, they bypassed the filter and pumped the mixture into five-gallon containers which were then dumped into the pool, diluting the mixture to safe levels.

After air levels in the basement were determined to be safe, the school was turned over to the Board of Education at 1:30 p.m., Colangelo said.

Children remained out of Gaskill the entire school day, district spokeswoman Judie Gregory-Glaser said.

School is scheduled to resume at Gaskill today.