A teenager has been arrested on suspicion of attempted murder following reports of a stabbing in Cambourne.
Police were called at about 10pm on Friday to reports of a stabbing in High Street.
Officers and paramedics attended the scene. The victim, an 18-year-old man, was taken to Addenbrooke's Hospital, in Cambridge, where he remains in a serious, but stable condition.
A 15-year-old boy has been arrested on suspicion of attempted murder and remains in custody, police confirmed.
Detective Inspector David Savill said: "I understand that there will be concerns within the community with regard to this incident.
"Community reassurance is a priority within this investigation and additional officers will be utilised to undertake both the investigation and to provide that visible reassurance.
"Additional patrols will be in place over the weekend in the area of Cambourne and I would encourage members of the public who have specific concerns to engage with officers.
"I am particularly keen to speak with anybody who has information about this incident. Whilst knife-related incidents are extremely serious and are the subject of national attention, they remain rare in the context of other crime types and especially so in Cambridgeshire."
Anyone with information regarding this incident should call police on 101 quoting 35/35967/19 or visit www.cambs.police.uk/report. Alternatively, contact Crimestoppers, anonymously, on 0800 555111 or via www.crimestoppers-uk.org.