A teenager was arrested on suspicion of attempted murder after a man was found with serious knife wounds.
The 18-year-old was found in Hill Lane shortly after 1am on Sunday with injuries to his back and his wrist.
These are thought to have been caused by a knife.
He was taken to hospital by the ambulance service, where he remains in a serious but stable condition, Hampshire and Isle of Wight Constabulary confirmed.
Officers arrested a 17-year-old boy from Southampton on suspicion of attempted murder and he is in police custody.
A cordon was put in place by police outside Springhill Catholic Primary School in Milton Road.
This was lifted shortly before 2pm on Sunday.
Speaking at the scene, Southampton residents described their shock at the news.
A resident of Milton Road, who wished to remain anonymous said: "I came out of my flat and my neighbour was telling me someone had been assaulted.
“It is usually a pretty quiet road but to hear someone has been attacked is awful."
Reacting to the attempted murder arrest, they added: "That is awful, especially if they are so young.
"I hope the person that was hurt will get better soon."
Police officers patrolled the road and surrounding streets, remaining in the area for most of the day.
Four police cars were parked at the scene.
A man, who wished to remain anonymous, said: "I saw police were here earlier when I walked by but haven't seen anything other than that.
"It is crazy that things like this can be allowed to happen."
Another passerby added: “It is worrying and I hope the person involved is okay.”
Following the attack, police urged any witnesses or those with information to come forward.
A spokesperson for the force said: “Perhaps you were driving through the area and have dash cam footage that may have captured something?
“We are carrying out house to house and CCTV scoping in the area but are urging residents to please check Ring Doorbell and CCTV footage.
“If you have any information please call us on 101 quoting 44240489487. Alternatively, you can go online and submit information on our website.
“Information can also be submitted 100 per cent anonymously via the independent charity Crimestoppers, by calling 0800 555 111 or by visiting their website.”
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article