What we know about double stabbing at school

A 13-year-old boy has been arrested following a double stabbing at a school in northwest London.

Two boys, aged 12 and 13, are in a serious condition in hospital after Tuesday's attack in Brent. Police launched a search for the suspect, and officers later detained a 13-year-old boy on suspicion of attempted murder.

Follow the latest updates on attack The investigation is being led by counter terror police, although a terrorist incident has not been declared. Here's everything we know so far.

What happened at the school? Police were called to Kingsbury High School around 12.40pm after a report that a 13-year-old had been stabbed. Officers then became aware that a second boy, aged 12, had also been stabbed.

The Metropolitan Police said officers began a search for the suspect - identified as a teenage boy - after he left the scene. Shortly after 6pm, Detective Chief Superintendent Luke Williams confirmed in an update that a 13-year-old boy had been arrested on suspicion of attempted murder.

A weapon was also recovered. Who are the victims? The two stabbing victims were taken to hospital in a "serious" condition, with one taken to a major trauma centre as a priority.

The identity of the boys, who are aged 12 and 13, remains unknown. The London Ambulance Service (LSA) was called to the school at 12.41pm.

"We sent resources to the scene including ambulance crews, incident response officers, an advanced paramedic, a paramedic from our tactical response unit and a clinical team manager," the LSA said. "We also dispatched a trauma team in a car from London's Air Ambulance.

"We treated two patients in total. We took one patient to hospital and the other as a priority to a major trauma centre." Who is the suspect? Police have arrested a 13-year-old boy on suspicion of attempted murder.

The boy - whose identity is not known - remains in custody for questioning by police. What have police said? DCS Williams said police are "keeping an open mind as to any motivation behind the attack".

He said the investigation was being led by counter terrorism police, though a terror incident has not been declared. He said counter terror officers are "working closely with our local officers in response to this incident".

"The investigation has not currently been declared a terrorist incident, and the investigation team will now be working at pace to gather any evidence and to establish the full circumstances of what's happened as quickly as possible." Read more from Sky News:Afghan asylum seeker found guilty of raping 12-year-old girlDrug dealer inspired by Home Alone rigged house with booby-traps What has the school said? Kingsbury High School head teacher Alex Thomas told parents that Tuesday's events marked a "deeply traumatic event for the whole school community". In a letter to parents, Mr Thomas said pupils at the lower school had been kept on the playground at the request of the police while they began their investigations.

He added that the lower school will be shut on Wednesday, but the upper school will remain open for students in years 10 to 13. The school released a statement at about 4pm saying that the "serious incident" was under control and it was not possible to enter or leave the school site..