Police were called at about 08:30hrs on Wednesday, 27 September to reports of a 15-year-old girl stabbed on Wellesley Road in Croydon.
Officers, the London Ambulance Service and London’s Air Ambulance attended.
A London Ambulance Service spokesperson said: “We were called today (27 September) at 8:33am to reports of an incident on Wellesley Road, Croydon.
“We sent a number of resources to the scene, including three ambulance crews, an incident response officer, and an advanced paramedic in a car. We also dispatched London’s Air Ambulance.
“We treated a teenager, but very sadly, despite our best efforts, she died at the scene.”
Chief Superintendent Andy Brittain, in charge of local policing, said: “Our immediate thoughts are with this young girl’s family who are facing the most tragic of news. Our officers are with the girl’s family to support them.
“My officers were immediately on scene to provide first aid and support paramedics.
“I am in contact with the local community, who are clearly as concerned as we are about this tragic incident. I shall continue to update them throughout the day.
“Acting on information provided to them, officers also worked closely with colleagues from across the Met and the British Transport Police to track a teenager in connection with the stabbing. I can confirm that an arrest was made at about 09:45hrs in the Croydon area. At this early stage we believe that he may have known her.”
Jason Perryi, Mayor of Croydon, said on X (formerly Twitter) that he is devastated to hear the incident and continued: “A suspect, who is believed to have known the victim, has been arrested, and I would like to thank all those who responded so quickly to the incident. I urge anyone with information to contact the police on 101 or report anonymously to Crimestoppers on 0800 555 111.”