Maine student passes out, 11 taken to hospital as cause of illnesses remains unknown

Eleven third- and fourth-grade students were taken to the hospital on Thursday as a precautionary measure after reporting "respiratory distress," despite the fact that investigators could not determine a possible cause of illness.

Emergency medical services were called to the scene just after 10 a.m., and the 11 students were taken to hospital "for further evaluation and precautionary measures," Scarborough schools' Superintendent Dr. Diane Nadeau said.

Students and staff had "made a full return" to the building as of Monday afternoon, Nadeau said. 

"We did meter the building twice from two different fire department meters as a redundancy, just to make sure," Kindelan said. "And there were no hazards found in the building or in the area of the incident."

"The school does have fire detection and carbon monoxide detection in the areas that it's required," he continued. 

The school's superintendent said the temperature was not assessed at the time the students were grouped together on the risers. She was unclear if the school concert would go on Thursday evening. 

Fox News' Jennifer Johnson contributed to this report.