A pupil at Southfields Academy has spoken of the terror which swept through the school as armed men  waved knives yesterday afternoon and stabbed a 15-year-old schoolboy.

The teenager was stabbed in the leg and taken to hospital on Tuesday after the attack at the building in Merton Road. 

Yesterday: Stabbing inside Southfields Academy

According to a pupil, staff and pupils desperately tried to keep the group out.

The pupil said: "There was a gang of boys with knives trying to get into the school to attack someone.

"Teachers and some of the pupils were holding the doors shut to try and keep them out but they were waving knives and threatening to stab the teachers.

“Teachers told the pupils to get back because they were trying to protect them.

“It was terrifying seeing teachers, who are supposed to be able to protect us, so helpless and now I don’t really want to go school.

“They boy they stabbed wasn’t who they were after so I’m scared that they, or others, will come back.

“All of my friends are really upset, why do they have to do this at our school?

“School won’t feel the same anymore, I used to feel safe there, now I don’t."

The Metropolitan Police and London Ambulance said they had attended the school and a 15-year-old was being treated for non-serious injuries. 

A statement on the school's website said: "Last night after school had ended for the day one of our students was attacked as he made his way home by a group of teenagers who are not pupils at the academy and do not have any connection with the school.  

"Our student suffered a stab wound to the leg and is currently being treated in hospital, fortunately he is expected to make a full recovery and we are supporting him and his family in every way we can.

"This was obviously a very serious incident and we are working very closely with the police to ensure the continued safety of our pupils at all times.  

"We understand that a number of arrests have already been made in connection with this incident."

Three teenage boys, aged 15 and 16 were arrested on Tuesday afternoon, with a fourth teenage boy aged 16 arrested overnight. 

They were not pupils from Southfields Academy. 

All four remain in custody. 

Police recovered three knives.

Did you see the attack? Call the newsdesk on 020 8722 6335.