The John Carroll School was closed Tuesday for additional testing to determine why 18 students were hospitalized Monday. The new tests did not uncover any environmental issues in the building, and the school is scheduled to reopen Wednesday, school officials said.

School officials abruptly closed the private Catholic high school Monday around noon when numerous students began to fall ill for unknown reasons.

Bel Air Volunteer Fire units and mutual aid personnel helped evacuate, triage and treat the students who became ill and initiated an investigation into the cause of the incident.

Testing by the fire department and hazmat personnel did not identify any hazards that could have caused the illnesses, fire officials said in a Facebook post

Kathy Walsh, chief advancement officer of The John Carroll School, said the school requested six members of the Harford County Department of Emergency Services’ Special Operations Team to begin a second check of the entire building at 6 a.m. Tuesday out of an abundance of caution.

Walsh said the officials used multiple meters measuring for a variety of different environmental health hazards and found normal readings on all meters. Those results were similar to the ones obtained Monday.

“As we have confirmed this is not an environmental issue, the building is now open,” Walsh wrote in an email response.

After-school activities resumed Tuesday afternoon and the school was scheduled open at its normal time Wednesday, Walsh said.

Walsh did not disclose symptoms of the hospitalized students and their current health status.

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