PUPILS were evacuated from a secondary school when three students and a teacher began to experience breathing difficulties.

All four suffered an allergic reaction at Chichester Free School in Hunston Road, Chichester, yesterday afternoon.

Police, paramedics and fire crews attended the scene with two of the affected pupils being taken to hospital for treatment.

Police said their symptoms were "believed to be caused by aerosols being sprayed".

The school said an "unknown substance" have been involved in the incident.

Principal, Louise New, said: “In the secondary phase of the school there were four allergic reactions which required the presence of ambulances and response medics.

“We acted on the advice of the emergency services to evacuate the whole school to their outside zones.

“The year group bubbles were not broken during this procedure and I am very proud of the mature response from all of the pupils.

“Following investigations carried out by the emergency services, all pupils returned to class.

“The emergency services have praised the school’s swift response to this incident and the pupils’ calm and mature behaviour throughout.”

Sussex Police officers were called to the scene shortly after 1pm.

The force confirmed that there are no serious concerns for any of those affected by the incident.

Enquiries are now ongoing to establish whether or not any offences had been committed during the incident.

A spokesman said: “Two teenage pupils – both of whom have existing conditions or allergies – were taken to hospital with breathing difficulties, believed to be caused by aerosols being sprayed.

“A teacher also reported the same symptoms and was checked over by paramedics at the school, however there are no serious concerns for any of those affected.

“The school was evacuated as a precaution but emergency services stood down from the scene about 3.30pm the same day.

“Enquiries are ongoing to establish the full circumstances, and to determine whether any offences have been committed.”

Crews from West Sussex Fire and Rescue Service rushed to the school following reports of “pupils suffering an allergic reaction to an unknown substance”.

Engines from Chichester and Bognor were sent to the scene with the firefighters worked alongside police and ambulance teams to ensure the safety of the students.

A fire service spokesman said: “Investigations were carried out to ensure there was no further risk present. Crews ensured the area affected was well-ventilated.

“There is not believed to be any wider risk to school pupils or staff, or the general public, as a result of this incident, and lessons have since resumed as normal.”