HOUSTON (NYTIMES) - Twenty-six people were hospitalised with breathing problems or skin irritation after they were exposed to bleach and sulphuric acid on Saturday (July 17) afternoon at Six Flags Hurricane Harbour Splashtown, a water park in Spring, Texas, authorities said.
One person was in critical condition on Saturday evening, said Ms Rachel Neutzler, a spokesman for the Harris County Fire Marshal's Office.
Authorities evacuated the park, which is north of Houston, at about 3.30pm local time.
Ms Neutzler said investigators did not believe the exposure to the chemicals, which are used to maintain pH balance, had been the result of an intentional act. She said it had occurred in a shallow pool intended for children.
Mr Scott Seifert, chief of the Spring Fire Department, said that authorities had decontaminated more than 60 people by having them massage their eyes and wash off under the hose of a ladder truck.
Mr Seifert said the breathing problems had been caused by a combination of 35 per cent sulphuric acid and 10-13 per cent bleach.
Investigators were examining a system at the park that injects chemicals into the water to maintain a pH balance of 7. When authorities arrived, they tested the water, and the pH balance was 7, said Harris County judge Lina Hidalgo.
"So that's why we don't know exactly what happened prior that made people sick," she said at a news conference.
Ms Neutzler said that bleach and sulphuric acid were both used to help keep pools clean and to maintain a balanced pH but that investigators "are looking into the system that injected these chemicals in the pool to see if there was a malfunction or not, but that's still under investigation".
Judge Hidalgo, the county's top administrator, wrote on Twitter: "We've issued a closure order to investigate and ensure the park meets all requirements before reopening again."
The park will be closed until the investigation is complete, authorities said.
Six Flags said in a statement that "a small number of guests in a section of the park reported feeling ill with respiratory irritation".
The company said: "The safety of our guests and team member is always our highest priority and the park was immediately cleared as we try to determine a cause."