RAMAPO, N.Y. (CBSNewYork) – There was a scare at a high school in Rockland County Thursday morning.

Authorities say nearly two dozen people were exposed to pepper spray at Ramapo High School.

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Emergency responders including the county’s HAZMAT were at the scene all morning Thursday investigating the source of the chemical.

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Police say 20 people were exposed. Nineteen were treated on the scene, and one was taken to the hospital.

Students were evacuated and taken to other schools and waited on buses. Just before noon, they were allowed to return to the building.

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“The Fire Department has confirmed that today’s 8:37 a.m. emergency evacuation at Ramapo High School was due to a pepper spray release and has determined the building safe for occupancy.  Students were temporarily relocated, but have since returned to Ramapo High School.  All normal activities will resume as scheduled,” said Tom Carton of the East Ramapo Central School District.