Three girls – two aged 13 and the third age 12 – were arrested on suspicion of assault and trespass after entering Cromwell Community College and “being violent and refusing to leave”.
One of the 13-year-olds was also arrested on suspicion of criminal damage.
“They have all since been released from our custody and bailed to return to us next year,” said a spokesperson for Cambridgeshire police.
All three girls are from March and travelled the nine miles to Chatteris where the incidents took place.
“We were called to Cromwell Community College in Chatteris by staff there, reporting a small group of students from another school had entered the school grounds, were being violent and refusing to leave,” said the spokesperson.
“Our officers arrested three girls, all from March, in connection with the incident.”
A 12-year-old girl and a 13-year-old were arrested on suspicion of assault and trespassing
A 13-year-old girl was arrested on suspicion of assault, criminal damage, and trespassing
Police are reviewing bits of evidence including one parent who told them “there was a man in his 20’s with them but he legged it (my kids were locked inside the school at the time)”.
Another parent has told police she understood the three teenage girls had made the nine-mile trip by taxi.
One Cromwell college parent told me: “My daughter was not told what was happening, but the teacher moved a table in front of the door.
“My daughter was leaning against a classroom window and the intruders came and banged on the window, then tried to get into the classroom.”
One other parent said: “I am mad that the school did not tell parents earlier.
“I am less worried about the ‘safety’ side because that can be fixed but I would have thought the school would have an easier time (fewer angry emails) had they told parents before the kids did.”
Another said his daughter asked “as soon as I got in if I had heard from school.
“She seems fine, but I think some kids in the same situation could be very shaken and no comms meant there is no way for parents to talk to kids and reassure them.”
On social media, one parent said her son came home school from saying the group of intruders comprised three girls and two older boys.
Her son was doing PE in a field “and had to run to the nearest safety point which was the primary school.
“He said two teachers were attacked but not hurt.
“I have since found out other students have told parents the same as what he is said. Crazy.”
Students were told to remain in their classrooms until the intruders had been taken away by police.
Executive head Jane Horn emailed parents of the 1,200 students with brief details about the incident, but some parents have told me they believe they should have been notified much earlier.
Ms Horn denied reports that the intruders were carrying knives and had attacked a teacher.
However, one parent told me tonight: “This plays the incident down somewhat, based on what my daughter and the children of other parents I’ve spoken to have said.”
The parent said there was “a failure of lockdown procedures; the communication with parents was non-existent.
“The people who were ‘uninvited’ (as the head says in her email) made threats and they were armed.
“They forced their way into classrooms, and at least one teacher was physically assaulted.”
Ms Horn said in her email that “I am aware that children have come home this evening with reports of an incident in school today.
“For clarification there were a group of young people who came into the college uninvited.
“The police were called and because it was so close to lunchtime, they asked that we keep the children in classrooms for a short while as it would be easier to apprehend the uninvited children.
“This was successfully achieved, and they were taken away.”
Ms Horn added: “I have heard that there are various rumours including attacks and the carrying of knives which is not an accurate report.
“This is now in the hands of the police and there is an ongoing investigation which I am sure you will understand, I am not at liberty to discuss.
“I can tell you that staff took swift and decisive action and whilst I fully understand this may have caused concerns to pupils, please be assured that this has been dealt with most firmly.
“I would like to take this opportunity to recognise the pupils of Cromwell who were very sensible and supportive of staff during the day, and it reiterates what a fantastic community we have here at Cromwell.”
