North Yorkshire Fire and Rescue Service say its Hazardous Materials Specialist Officers are investigating the incident at Outwood Academy, along with crews from Ripon and Boroughbridge.
A specialist detection, identification and monitoring (DIM) team from West Yorkshire Fire and Rescue Service is also working alongside them.
It has been confirmed that two of the 27 pupils affected were taken to hospital, the rest were treated at the scene by ambulance staff.
We are working with colleagues from North Yorkshire Police and Yorkshire Ambulance Service at this time to determine what has caused this occurrence. Further information will follow as we have it.
Emergency services remain at the scene at Outwood Academy School on Clotherholme Road in Ripon.
Police were called at around 12.30pm - its is believed the incident happened sometime between 11am and 11.30am. A number of students had collapsed at the school and a number of others were taken ill. It is reported 27 students have been affected, all displayed signs of sickness and feeling faint. Some have been attended to by paramedics at the scene and others have been taken to hospital.
At this stage it is not known what has caused the students to fall ill and officers are working with the fire service to establish what has caused the incident.
It has been confirmed that 27 pupils and one teacher have collapsed at Outwood Academy School in Ripon. The school has been evacuated and pupils sent to nearby Ripon Community College. Emergency services remain at the scene.
Emergency services are currently in attendance at the Outwood Academy School on Clotherholme Road in Ripon.
Police received reports at around 12.30 today that several students had collapsed at the school. A number have been taken to hospital.
A spokeswoman for North Yorkshire Police said the safety of all the students and staff at the school was paramount and officers were working with the fire and ambulance services to establish what has caused the students to collapse.
Governors at Mablethorpe's only secondary school have voted in favour of pushing ahead with a formal consultation to close it.
ITV Calendar has been told the closure plans for Monks' Dyke Tennyson College are due to a £1.4 million deficit and falling pupil numbers. Students will instead be taught at the school's other campus in Louth.
An action group has already held a protest, and it says there is growing support for the school to become a 'free school academy'.
Bradford's National Media Museum is to benefit from a funding boost to create a new interactive science gallery.
The museum, which was threatened with closure just two years ago, will get £1.5 million to start a hands on exhibit exploring the science behind light, sound and perception and how they impact what we watch on tv.
Reasearch into fighting heart disease at the University of Leeds has been given a funding boost.
The British Heart Foundation has committed £1.3 million to research into finding ways to reduce the risk of heart disease in people with diabetes.
Around 280,000 people in the region are thought to have diabetes, which increases their risk of cardiovascular disease.
Campaigners have marched through Leeds - protesting against the Government's scrapping of grants for half a million students.
1900 students in Leeds alone will be affected when the Student Maintenance Grants are stopped in September next year. A third of students surveyed said they would have to drop out of higher education if they were not given the money.
Dozens of schoolchildren from across Lincolnshire are taking part in an archaeological dig in Bardney, working with Prof Carenza Lewis from The University of Lincoln who also features within the well-known TV programme 'Time Team'.
The work is aimed at inspiring more youngsters to go to university as Lincolnshire has a low take up in the county.
The students and their teachers have already found bone, buckles and medieval pottery as part of the dig.
Bradford has handed out more fines to parents for taking their children out of school than almost any other authority in the country.
It was just behind Lancashire, in a report published today, dishing out 3,319 fines in 2015-2015.
Councils said schools across the country have been handing out more fines as part of a crackdown by the Department for Education and regulators Ofsted on term time absences.
It is down to the individual headteacher whether to hand out a fine, but many are increasingly resorting to the punishment.