A 14-year-old girl has been charged in connection with three stabbings at a school in north Manchester, police said.The girl was charged with three charges of attempted murder and two charges of possessing a bladed article on school premises over the incident on Tuesday.She will appear at Westminster magistrates court on Friday.Police have confirmed that a counter-terrorism unit is leading an investigation into the stabbings.The girl was arrested after two students and a staff member were stabbed at the Co-op academy in Blackley on Tuesday morning.Earlier, Greater Manchester police said the suspect had been arrested on suspicion of assault and detained under the Mental Health Act.Detectives are “keeping an open mind to the motivation of the attack” and have not said it was a terrorist incident.Ch Supt David Meeney, the city of Manchester’s district commander, said: “Since our last update, further information has come to light that we have made Counter-Terrorism Policing North-West aware of.”Meeney added: “There is no information to indicate any further threat, and our local officers continue to be in the area. We are here to listen and to act, so please speak to our officers with any concerns.”The injuries sustained by the two students, a boy and a girl each aged 14 – as well as a 27-year-old male staff member – were consistent with stab wounds but were “non-serious”, police confirmed.Students were put into lockdown and told not to leave their classrooms after emergency services were called to the scene.Within an hour of the stabbing, a large crowd of students, parents and passersby had gathered outside the school.Some parents said they had not been told anything by the school and had been forced to piece together what had happened through texts and calls from their children as they were kept in their classrooms.In a message sent to parents, the school stated that an “incident” had taken place but everyone was safe.The three people who were injured have all been discharged from hospital.