Police are hunting a teenage boy after a teacher was attacked with a knife at a Bradford school.
The 50-year-old male teacher at Dixons Kings Academy was taken to hospital with a stab wound after the attack, which occurred around the start of the school day.
His condition has been described as stable, with no internal bleeding.
Officers are seeking a 14-year-old boy, described as Asian with short dark hair. He was last seen wearing a blue uniform blazer.
In an updated statement, the school said its thoughts were with the wounded teacher and his family and praised pupils for responding with "tremendous maturity".
Education Secretary Nicky Morgan said violence of any kind in schools is "totally unacceptable", adding that her department is "ready and prepared to offer all necessary support".
Detective Superintendent Simon Atkinson, of West Yorkshire Police, said: "We are conducting inquiries in the area to locate a suspect and I would like to reassure residents and staff that all necessary resources are being deployed to investigate this ongoing and clearly very serious incident.
"We would like to hear from anyone who witnessed the incident or knows the whereabouts of the suspect.
"At this stage we do not believe there is an ongoing risk to pupils or staff at the school. The rest of the school is continuing to operate as normal and local officers, including safer schools officers and members of the local area neighbourhood team, are currently at the school and are liaising closely with staff.
"We are also working closely with our partners in the local authorities to investigate the full circumstances of this incident, which will be the subject of a thorough investigation."
Police were called to the scene at around 8.55am by an ambulance crew responding to a report of a member of staff being stabbed.
The school's statement said: "Following authorisation from the police, we are able to release further details of the serious incident that occurred first thing this morning.
"A member of staff was assaulted with a knife by a 14-year-old student who then ran off the site. The member of staff is in hospital and his condition is described as stable, there is no internal bleeding. Our thoughts are with him and his family at this time.
"We are working very closely with the police and our main priority at the moment is the well-being of our student and staff community and reassuring our parents. All students are safe and calm and have responded with tremendous maturity during a very difficult time.
"Thank you to parents for the overwhelming support you have given us today. We will continue to update you as and when we are given more information."
Ms Morgan said: "My thoughts are with the injured teacher, his family, colleagues and the pupils at the school. My officials are currently in touch with the school and keeping me constantly updated on the situation and my department is ready and prepared to offer all necessary support.
"Violence of any kind in schools is totally unacceptable and this Government is committed to building on the significant measures we have already taken to make sure our schools are safe for everyone in them."
Mary Bousted, general secretary of the Association of Teachers and Lecturers (ATL), said she was "shocked and incredibly sad" to hear of the incident.
"Thousands of dedicated teachers are working in schools and colleges with our children and young people every day, and they should never have to face verbal or physical violence," she said. "Thankfully today's events are extremely rare and schools are usually safe places for children and adults.
"When we learn more about the circumstances, it may be that there are lessons to be learned, but for now, the teacher and his family, the pupils, staff and their families need our support."
Kevin Courtney, deputy general secretary of the National Union of Teachers, said: "This is a dreadful incident. Our thoughts are with this teacher and his friends and family and with the students and colleagues at the school. It is always important to reflect on incidents like this to see if anything could have been done to prevent them, but to bear in mind that our schools are, in the main, places of calm and safety."
The attack comes a year after teacher Ann Maguire, 61, was stabbed to death by one of her pupils, Will Cornick, as she taught a Spanish class at Corpus Christi Catholic College in Leeds on April 28 last year.
Cornick, who was 15 at the time, was sentenced to a minimum of 20 years in prison before he is considered for release.
Dixons Kings Academy was formerly the Kings Science Academy and joined the Dixons chain earlier this year. Kings Science Academy, which was visited by Prime Minister David Cameron in 2012, was one of the first 24 free schools to open in 2011.
But it later hit the headlines after allegations of fraud emerged.
The school's founder and principal Sajid Hussain Raza was charged by the Crown Prosecution Service (CPS) with fraud and other offences relating to his involvement with the Kings Science Academy. Raza was arrested last year following an investigation into the school.
David Green, leader of Bradford Council, said: "The stabbing of a teacher at Dixons Kings Academy has deeply shocked and traumatised students, school colleagues and the wider community. Our thoughts are with them and the teacher's family and friends."