Perkins said that at about 1 p.m., students in a classroom at the school, located at 1111 Camino Pablo, were conducting experiments with household products when one boy spilled some bleach and vinegar on his desk and "took a big whiff of it."
The boy was given oxygen and taken to a local hospital, and is doing fine, Perkins said.
While this was happening, other children started pouring their chemicals into a sink, which caused them to be mixed together.
When firefighters asked if anyone else was feeling sick, 10 more children raised their hands, Perkins said.
Their parents were called to the school to pick them up, Perkins said, but none of them appeared to need any medical care.