Detectives are hunting for a teenage schoolboy after a teacher was stabbed in front of pupils in a classroom.
The 14-year-old boy allegedly attacked the male teacher with a knife smuggled into school.
A 50-year-old teacher at Dixons Kings Academy in Bradford was takenwith stab wounds to the chest to hospital, where he remains and is said to be in a stable condition.
Teachers appealed for the schoolboy to hand himself in to police.
Speaking outside the school gates, the academy's executive principal Nick Weller said: "It happened right at the beginning of the school day and there were some students who witnessed it. A few students witnessed it - in a classroom.
"Those students have been interviewed by the police.
"Obviously, it's a very shocking thing for them to see. The general atmosphere in the school is very calm, quite orderly, we're trying to keep to normal routines as much as possible."
Mr Weller said there was nothing in school that suggested the attack was going to be launched.
He said: ''I think there was some....the police are looking into the lead up to this incident, there was nothing in school that led up to it - there may have been other people outside the school who maybe knew something.''
Mr Weller said a member of staff is at the hospital with the teacher while counsellors are on site supporting pupils.
He confirmed the suspect is a pupil at the school and has been there a year.
Parents arrived at the school - which is next to the city's ambulance station - to check if their children were OK.
Tahir Jamil emerged saying he had been reassured that his 15-year-old daughter was safe and meeting staff with around four other families.
''They've explained everything to us now,'' he said.
''Two of the teachers came out and explained everything to us.
''They didn't tell us what teacher it was but now I'm satisfied. I wanted to take my daughter with me but they assured us that the school is safe.''
A number of uniformed police officers could be seen coming in and out of the school, which is about a mile-and-a-half from the city centre.