A 15-year-old girl suffered a stab injury after she was reportedly attacked by a "masked" man outside an Eltham school. 

Eltham Hill confirmed the incident took place outside the girls' secondary this afternoon, with police arresting a male, believed to be in his teens, nearby on suspicion of GBH.

The victim sustained non-life-threatening injuries to her leg, for which she has received treatment.

A statement sent to parents reads: "I am writing to let you know there was a very serious incident outside Eltham Hill School at the end of the school day today.

"A young man wearing a mask attacked one of our students by the Bingo Hall as she was leaving school and obviously other students who witnessed this were extremely frightened.

"The young man was carrying a knife and one of our members of staff along with a member of the public managed to get the knife of him.

"Our student is injured but is going to be fine and is receiving medical attention.

"The person responsible ran off but is now in police custody and the police investigation is ongoing."

Police were initially called shortly after 3pm after a member of the public reported a sighting of a man armed with a knife.

A police spokesperson said: "Officers responded and detained a male matching the male’s description, believed to be aged in his teens, on Eltham Palace Road.

"Police Taser was deployed and discharged. The male was taken to hospital as a precaution before going into police custody on suspicion of GBH.

"A 15-year-old girl was found suffering from a stab injury to her leg in a nearby school. Her condition is not thought to be life-threatening.

"Enquiries continue to determine whether the incidents are linked."