The teacher died in hospital after the stabbing at Corpus Christi Catholic College
A female teacher has been stabbed to death at a school in Leeds.
Police said a 15-year-old male pupil at Corpus Christi Catholic College in Neville Road has been arrested.
The woman, who has not been named, was taken to hospital but later pronounced dead.
Det Supt Simon Beldon, of West Yorkshire Police, described the stabbing as an "isolated incident" and said there was "no ongoing risk to pupils or staff".
The call to police came from the ambulance service shortly before 12:00 BST.
Mr Beldon added: "The situation is under control and officers, including safer schools officers and members of the local neighbourhood policing team, are currently at the school and are liaising closely with staff."
He said the "rest of the school is continuing to operate as normal".
The BBC's Danny Savage says Corpus Christi is known
as a good school in a problematic area
Mr Beldon stressed that parents of pupils at the school should "not attend the site unless directly requested to do so by the school".
The college has 950 pupils and according to its website it retains "traditional values", describing these as "a strong Christian ethos, a broad and varied curriculum, good teaching and learning, excellent discipline and outstanding pastoral care".
Mr Beldon said inquiries at the school were at "a very early stage but the full circumstances of this incident will obviously be the subject of a full and thorough investigation".
The BBC's Danny Savage said the school was on a large estate to the east of the city, well known to residents.
"It's regarded as a good school in what in the past could be regarded as a problematic area overall," he said.
Tom Riordan, chief executive of Leeds City Council, said: "We are aware of the serious incident at Corpus Christi Catholic College this morning and our thoughts are with all those concerned."
He added: "We are working with the school to support pupils and staff at this very upsetting time."
Mr Riordan said the authority was "working closely with the police and helping with their investigation".