Three people have been arrested and two men rushed to hospital after a ‘serious assault’.
It comes as police taped off an alleyway outside a popular ice cream parlour this morning.
Forensics officers were seen outside Scoops in Elm Grove, Southsea, at around 10.30am.
Hampshire police, who confirmed it was a stabbing attack, have now said two men were attacked in Grove Road South at 4.30am today.
Parts of nearby Belmont Street have also been taped off by police.
A 32-year-old man was taken to Southampton General Hospital and a 27-year-old man was taken to Queen Alexandra Hospital.
The men, from Portsmouth, sustained serious but not life-threatening injuries.
A spokesman said a 19-year-old man and a 16-year-old boy, both from Redhill in Surrey, and a 33-year-old man from Heston in Middlesex were arrested.
They are in custody, he added.