A male teacher is in a stable condition after a suspected stabbing at Tewkesbury Academy in Gloucestershire
Police say they were called just after 09:00 BST, and a teenage boy was arrested on suspicion of attempted murder at 11:00
He was arrested by firearms officers in Stoke Orchard, five miles away from the school
One teacher kept his pupils safe by sitting in front of a classroom door and barricading it, a parent says
Pupils were locked down after the incident, but have now been allowed to leave
Tewkesbury is a state school for 11 to 18-year-olds
Tewkesbury School is a co-educational state academy in Gloucestershire, open to pupils aged 11 to 18, in the town of the same name.
The school is located along Ashchurch Road, which connects the town to the M5 motorway.
The PA news agency reports that a convoy of six unmarked police 4x4 vehicles - believed to contain armed officers - has left the school.
In an updated statement, a spokesperson for the school says they will follow police guidance in "how to ease the lockdown before releasing students to return home".
The school says staff were alerted to the alleged stabbing shortly before 9am.
School leaders immediately contacted police, it adds, and placed the site under lockdown "in line with our robust safeguarding procedures".
“Police have been on site throughout the morning and supporting us to ensure pupils were kept safe and secure while the incident was investigated."
The spokesperson says the school is grateful to staff, parents and students for their "patience and understanding during what has been a difficult morning".
They say their thoughts are with their injured colleague and "we wish him a swift and successful recovery".
A male teacher has been taken to hospital from a school in Gloucestershire with a "suspected stab wound".
Developments are moving fast, so here's a re-cap:
We will bring you any further details as we have them.
In a statement, the school's headteacher Kathleen McGillycuddy says: "We appreciate that this morning has been a worrying time for all associated with Tewkesbury Academy. We are writing to reassure you that all pupils remain safe and well.
"We were alerted shortly before 9am this morning to reports of a serious incident which left a male member of staff in need of hospital treatment.
"The school was locked down and police were called immediately when we became aware of this incident. We have since been taking advice from the police on when and how to share updates with you.
"In the last few minutes police have arrested a teenage boy in connection with this incident. In conjunction with police advice the lockdown remains in place as a precaution. We hope to be able to provide a further update once cleared by police in the near future.
"Thank you for patience and understanding at this difficult time."
Tewkesbury MP Laurence Robertson tells the BBC the school incident is "very shocking, very sad and worrying. My heart goes out to everyone who is involved."
He adds: "Weapons have no place in a school or society... Tewkesbury is a very peaceful area, it’s law abiding."
"This is a very big shock," he continues, adding that the school where the stabbing happened is "very well-known. They carry out extraordinary work. This is such a surprise."
Education Secretary Gillian Keegan says she is "deeply concerned" by the reports.
"We are closely monitoring the situation and remain hugely grateful to the emergency services who are currently on the scene," she says.
"My department is on hand to support the school as the situation unfolds."
We have just recived a statement from the South Western Ambulance Service NHS Foundation Trust.
Paramedics were called at 09:08hrs, it said.
Three "double-crewed land ambulances and two operations officers" were sent to the scene.
"We conveyed one patient by land to Gloucestershire Royal Hospital," it added.
The hospital is around 12 miles from the school.
Edward Rowe
Reporting from Tewkesbury School
I'm at Dobbie's car park where parents of children from Tewkesbury School are waiting for an update.
There's about half a dozen police here and more than 100 family and loved ones waiting to hear if their children will be allowed out of the school, which is currently in lockdown.
Police are advising parents or carers of pupils at Tewkesbury School to go to the car park.
Edward Rowe
Reporting from Tewkesbury School
I'm on Ashchurch Road just outside Tewkesbury School.
There is a steady stream of traffic coming across the school and looking at what is going on inside.
A lot of police cars are outside at the moment, and there are a few ambulances as well.
Lots of parents are on the road outside the school.
It's not clear if pupils are still in the school - but overhearing snippets of conversations and talking to people, it seems there are still people inside.
Teachers at the nearby Tirlebrook Primary School say they have also enforced a lockdown.
"An incident has occurred this morning at Tewkesbury Academy and we have been advised by Tewkesbury Police to put in place a lock down," they said on Facebook.
"We have a police presence at school and are being fully supported at this time. We would like to reassure all families that children at Tirlebrook and Little Oaks are safe and well.
"We must ask that families do not come to school during this time as this could compromise the police operation currently underway and also compromise the safety of the children.
"During this situation all school staff will be supporting the children and liaising with the police so we would ask that you do not attempt to communicate with the school office.
"We thank you all for your support and will update you as soon as possible when we know more."
Welcome to our live coverage of the incident at Tewkesbury School in Gloucestershire, where an adult has been taken to hospital with a suspected stab wound.
The school is in lockdown.
We'll bring you the latest updates here.