A 13-year-old boy was arrested after another boy, aged between 13 and 14, was attacked in Roe Green Park in Kingsbury, north-west London.
The traumatised victim told police he was raped by the teen at about 9am yesterday morning in a wooded area in the park.
A Met Police spokesman said: 'Police investigating a rape in Roe Green Park, Kingsbury Road, at around 9am on Tuesday, have made an arrest.
'A 13-year-old was arrested on Wednesday, May 17 on suspicion of rape. He remains in custody at a north London police station.'
He added: 'The victim, a boy aged in his early teens, was assaulted by another male in the park.'
Police have launched a full-scale investigation into the sex assault, setting up a special tent at the scene and sealing off the park.
Hundreds of pupils at nearby schools were sent home early yesterday afternoon after the alarm was raised and students were warned to avoid the area.
One parent, whose teenage daughters were sent home early at 2pm, told the Brent & Kilburn Times: 'Teachers came into the classrooms and told pupils to take care when going home and to avoid the park.'
An email to parents and pupils at one school warned: 'An incident has happened in Roe Green Park and therefore we want to remind you of key messages to keep you safe.
'Where possible try not to travel alone. We encourage you to come to school on time, so you are travelling with the majority of our school.
'At the end of the day please let your parents know where you are going to be and ensure you have safe plans to get home with others.
'If you are feeling uncomfortable, seek help and/or come back to the school.'
Boy, 13, is arrested after a terrified schoolboy was raped in a London park in broad daylight Rachael Burford Mailonline 17 May 2017