A schoolgirl was taken to hospital following an incident involving a group of pupils at Helsby High School yesterday (June 25).
The Year 10 pupil is believed to have received treatment for facial injuries.
PC Dave Walton, of Western Rural Neighbourhood Policing Unit, confirmed police had been called to attend the school at 1.30pm, following the incident which he said involved four or five girls from Year 10.
He said police will continue their investigations today.
Headteacher John Dowler said: "The school is continuing to investigate an incident which took place in school yesterday. Some initial sanctions have been applied.
"The school is continuing to liaise closely with police on this matter."