Firefighters were called to the high school shortly before 8 a.m. after a report of a suspected carbon monoxide gas leak.
Classes resumed by 8:40 a.m. after officials determined the building was safe.
Caryn Furst, a spokeswoman for the Port Chester-Rye Union Free School District said a CO detector apparently went off in the kitchen and as a result Con Edison was called to check everything out.
"Meanwhile, following protocol (same one we would use if this happened at home), everyone was evacuated. The staff and students were back in school within an hour. All’s well," Furst said.
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