Four students at an all-girls Catholic high school in the Bronx were left “singed” by flames and hospitalized when their chemistry teacher performed an experiment that went awry, school officials and authorities said.

The 8:30 a.m. accident occurred at St. Catherine Academy in Allerton during first-period chem lab when the teacher executed the experiment using two substances — alcohol and some kind of metal, school president Sister Patricia Wolf told reporters.

“This morning an accident occurred during a demonstration … in which several students were singed by a flame,” Wolf said, noting that “the teacher was doing the experiment, not the students.”

Wolf added that the teacher, who was not identified, is “very experienced” and was “distraught” over the incident.

“An accident had happened and it was handled by the teacher appropriately,” said Wolf.

Four of the injured students, who are all 15, were rushed to Jacobi Medical Center, with two in serious condition from the burns, authorities said.

The worst-injured girl suffered severe burns to her face, hands, neck and hair, while another had some of her hair burned.

The two others suffered minor burns on their faces, according to officials.

The injured were accompanied by a school official to the hospital, said Wolf, adding that the class the incident occurred in was filled with mostly sophomores.

Following the incident, an “IRIS alert” was sent out to all parents explaining what had happened, said Wolf.

Wolf could not say exactly what kind of experiment the teacher was performing or what kind of metal the teacher was using.

“I’m not a chemist. I can’t tell you exactly what that metal was,” said Wolf.

The president of the 500-student school said: “It’s been quite a busy day.”