Police are investigating after a 15-year-old girl was raped on a school field in Dorchester in a terrifying night-time attack.

Detectives are now appealing for witnesses or anyone with information to come forward following a report of an attack in the field at St Osmund’s C of E Middle School on Barnes Way.

Police received a report at just before 10pmon Thursday night and the incident occurred shortly after 9.22pm.

The victim was walking along the field when it is reported that she was approached from behind by a man – who was carrying a Swiss army-style knife – and forced onto the ground before being sexually assaulted.

The offender is described as wearing a light grey Puffa-style jacket with the hood up, light coloured trousers and leather gloves.

A cordon was put in place to allow officers to examine the scene.

An investigation has been launched by detectives from Dorset Police’s Major Crime Investigation Team (MCIT).

Detective Inspector Wayne Seymour, of MCIT, said: “This was an extremely frightening incident for the victim and she is being supported by specially-trained officers.

“I am appealing to anyone who was in the area around the time of the incident and saw or heard anything suspicious to please contact us.

“I appreciate that this incident may cause some concern for members of the community, but I would like to reassure them that a full and thorough investigation is underway to identify the man responsible.

“Officers from the local neighbourhood policing team will be carrying out increased patrols in the area and can be approached with any concerns.”

Anyone with information is asked to contact Dorset Police at www.dorset.police.uk, via email 101@dorset.pnn.police.uk or by calling 101, quoting occurrence number 55190191713. Alternatively, contact Crimestoppers anonymously on 0800 555 111 or via www.crimestoppers-uk.org.