A 13-year-old boy suspected of stabbing two boys at a secondary school is a former pupil, police have confirmed.
He was arrested after being seen at a mosque, they added.
Police believe the attack began when the teenager, a British national, went into a first floor classroom at Kingsbury High School, in Brent, north-west London, and sprayed a substance towards a pupil who was not injured.
Chief Superintendent Helen Flanagan told reporters: "The suspect has then attacked another pupil, a 13-year-old in that classroom, stabbing him, and then the suspect has left, running down the hallway of the school.
"As he is leaving, he then attacked another victim, a 12-year-old, stabbing him before running off and away from the school."
Two boys, aged 12 and 13, were taken to hospital in a serious condition after the incident, which unfolded at lunchtime on Tuesday.
Counter-terror police have been leading the investigation into the attack but Ch Supt Flanagan said it has not been declared a terrorist incident.
She added that officers do not believe the suspect has "any particular connection" to the mosque.
"Police were called by a member of the public at approximately 4.50pm over concerns of a child that had been seen at a mosque in north west London," she said.
"Officers attended shortly after and arrested a 13-year-old boy on suspicion of attempted murder, and he remains in custody.
"At this stage, we think that it may have been coincidental that he ended up in that area, and all of those at the mosque have been incredibly supportive of this investigation."
Officers are understood to be leaning towards a personal grievance being the motivation, rather than terrorist ideology.
Searches have been carried out at two addresses connected to the suspect and the mosque where he was arrested. Police are also speaking to around 30 to 40 witnesses.
In a letter to parents, the school's head teacher said it was a "deeply traumatic event for the whole school community". Home Secretary Shabana Mahmood described the attack as "shocking".
(c) Sky News 2026: Boy arrested over double stabbing at Kingsbury High School in London is former pupil, police
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