A school has been evacuated and 100 people including dozens of pupils have been assessed by paramedics after the suspected “discharge of an aerosol”.
Two people were taken to hospital with breathing difficulties after the incident at St Paul’s Catholic High School in Manchester.
A spokesperson for Greater Manchester Police (GMP) said a 13-year-old girl has been arrested on suspicion of possession of a section 5 offensive weapon.
Firefighters from Greater Manchester Fire and Rescue Service used four sets of breathing apparatus and gas detectors to assess the scene.
They also assisted ambulance crews in triaging those evacuated from the school.
In a statement, the North West Ambulance Service said: “At 12.16pm the service was called to an incident involving a release of gas at St Paul’s RC High School, Wythenshawe, Greater Manchester.
“Due to the number of potential casualties and the resources needed at the scene, the trust declared a major incident.
“We sent 21 resources including emergency ambulances, our Hazardous Area Response Team (Hart), advanced paramedics, Merit doctors and volunteer services who between them assessed more than 100 potential patients.
“Of those, two were taken to Wythenshawe Hospital with breathing difficulties - none of the conditions presented to us were life-threatening.”
A spokesperson added that the “major incident” was stood down at 3.10pm and the trust is continuing to work with the Greater Manchester Fire and Rescue Service and GMP.
The school has been approached for comment.
