Plymouth pupil attacked by teenagers after school break-in
Three teenage girls broke into a Plymouth school and attacked a female pupil, police said.
The attack "spilled over from external incidents on a neighbourhood estate", a letter from Notre Dame School read.
Staff "intervened in the fight" and the student was left "shocked and bruised", head teacher Katherine White told parents.
Devon and Cornwall Police are investigating and school security has been increased for pupils' protection.
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Mrs White's letter, dated Thursday 3 December, read: "Your daughters and sons may have told you about a serious incident that happened yesterday lunchtime in school."
"Three teenage female intruders came on to our site to find a particular year 11 Notre Dame student. One of the intruders physically assaulted that student just outside the basketball courts."
School 'deeply shocked'
Mrs White said the school was "investigating the involvement of any Notre Dame student who may have instigated this recent aggression."
In a statement she told the BBC: "We have increased security measures for the protection of our pupils; in the short term this means locked gates with staff in attendance. We will be taking advice on further long term security measures this week."
"Our community was deeply shocked by the incident and we have taken serious and immediate action."
Devon and Cornwall Police spokesman said officers were called to a report of an assault at the school, at about 14:30 GMT on Wednesday.
"On arrival it was established that a 15-year-old female student had been assaulted by three girls from another school," he said.
"She was not seriously injured and police continue to investigate in conjunction with the school."