Police have confirmed that a 14-year-old schoolgirl arrested after a triple stabbing at a north Manchester high school has now been detained under the Mental Health Act, as an investigation continues into the incident.

Two pupils and a member of staff were injured in the attack at Co-op Academy Manchester on Plant Hill Road in Blackley, just a few miles from Oldham. Emergency services were called to the school shortly after the start of the school day on Tuesday morning.

The injured are a 14-year-old girl, a 14-year-old boy, and a 27-year-old male member of staff, all of whom suffered knife wounds. Their injuries were not deemed to be serious, and all three have since been assessed and released from hospital, Greater Manchester Police said.

The arrested girl, also 14, was originally held on suspicion of section 18 assault. In an update issued on Wednesday evening, GMP stated she had been detained under the Mental Health Act.

Chief Inspector Jon Shilvock, from GMP’s City of Manchester North division, said the investigation had “continued at pace” since the incident. He added: “Our thoughts are with those that were injured and were caught up in the incident. Whilst the physical injuries were not believed to be serious, we know the impact to those that were involved or were witnesses to this will be significant, and we want to reassure our community we are taking this very seriously.”

Officers have appealed for people to stop speculating about the incident on social media. The force said it was aware of posts circulating the names of those involved, which it described as “unhelpful” and likely to cause distress to victims and witnesses.

The Co-op Academies Trust, which runs the school, said the school was immediately placed into lockdown and staff acted “bravely” to detain a student before emergency services arrived. It confirmed the incident was isolated and there was no wider threat to the public.

In a statement, the trust said: “While our policies outline strict screening and search powers in line with Department for Education guidance, weapons can unfortunately be small and easily concealed without prior indicators. We had no reason to conduct a search on any student this morning.”

The school reopened on Wednesday, with emotional support available for pupils and a police presence in the area to reassure staff, students and the local community.

For Oldham families, the incident serves as a reminder of the robust safety procedures in place across Greater Manchester schools and the importance of reporting any concerns to school staff or the police. GMP has urged anyone with information that could assist the investigation to come forward.