Brianna Grady with her father Brian in front of Holy Child Jesus Catholic Academy on 86th Avenue in Richmond Hill. Brianna was one of 21 students taken to a local hospital after a mishap during a science experiment. View Full Caption DNAinfo.com/Ewa Kern-Jedrychowska

QUEENS — Twenty-one students were taken to local hospitals after an incident during a science experiment at a Richmond Hill Catholic school, officials said.

Children were treated for eye irritation and inhalation after one of the students accidentally mixed two substances that were not supposed to be combined inside a classroom at Holy Child Jesus Catholic Academy, at 111-02 86th Ave., near 111th Street, about 9:37 a.m., an FDNY spokesman said.

The sixth grade students worked on a science project, when one of them mixed hydrochloric acid and aluminum, which filled the classroom with fumes, students and parents said.

The teacher quickly took the children out of the classroom and called 911, said Stefanie Gutierrez, press secretary for the Diocese of Brooklyn.

"All of the kids [that were in the classroom] were taken to local hospitals and they are OK," Gutierrez added. "They were taken as a precaution and some of them have already been released."

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Brianna Grady, who was one of the students taken to the hospital, said that the experience was "a little bit scary."

"Some kids had difficulty breathing," she said.

Brianna's father, Brian Grady, said he was upset because he found out about the incident while watching the news.

Gutierrez said that she had no details as to how the mishap happened.

The school serves students from kindergarten to eighth grade, according to the school's website.