Co-op Academy in Manchester went into lockdown this morning after three people were "stabbed" in a serious incident. 

Multiple police cars were at the scene in Blackley, along with a helicopter hovering above as an ambulance treated the victims. 

Students are sheltered in their classrooms, parents said, as police responded to the incident. 

Police said a schoolgirl has been arrested, but the victim’s injuries aren’t believed to be "serious". 

Crowds of parents have arrived outside the school as families wait to take home their children. 

One mum wrote on Facebook: "The school has just called to ask permission if my son is allowed to leave the premises. So I trust that the threat must be over and is now safe." 

"Emergency services remain on scene, and we are supporting the school. There is not believed to be any wider threat to the pupils and staff in the school," the police said.