A Gold Coast school classroom has been quarantined and emergency services are on site after 23 children from a Year Four class began to display rashes.

Firefighters and paramedics are responding to an incident at Emmanuel College on Birmingham Road, Cararra.

Crews were called to the college at 9.30am (AEST) today when several children began to display rashes and complain of itching.

An emergency services spokeswoman said 23 children were being assessed and treated by paramedics at the site.

Officers had yet to confirm the nature of the substance but no children had been taken to hospital.

"Now that they are away from the substance they are improving," she said.

Queensland Fire and Rescue Service scientific officers are conducting air and sample testing in one classroom at the school.

The classroom has been quarantined while testing is conducted.