A 19-year-old is in a “serious condition” after being stabbed in Rochester High Street.
The teen was treated at the scene by paramedics before being taken to a London hospital where he remains.
A 20-year-old man was arrested in connection with the stabbing and an investigation is underway.
Police and ambulance crews were called at around 9.30am following reports of a serious assault.
A video taken by a passer-by shows a large emergency services response in the area, with at least seven police cars and a critical care car at the High Street’s junction with Star Hill. Police have also taped off the crossing outside Havel Surchi Barbers.
Detective Inspector Paul Fewtrell, of Medway CID, said: “Members of the public were involved in initially detaining the suspect and I am asking any of them who have not yet spoken to the police, to call our appeal line.
“We are also appealing for anybody else who may have witnessed this incident to contact us.
“It is understood some people may have taken photographs or videos on their phones and I would urge them to call us, rather than sharing any images online.”
Any witnesses or anyone with information should call the Kent Police appeals line on 01634 792209, quoting reference 12-0318.