A man is dead and 13 "violent people" are in custody following a brawl in Adelaide's central business district in the early hours of Anzac Day.
Assistant Commissioner John Venditto said a 25-year-old Victorian man was found lying on the road about 2am on Monday with multiple stab wounds to his chest.
He died shortly afterwards.
Police swarmed the area and made 13 arrests, including some of people wanted over other matters.
They are yet to determine whether the arrested men are linked to the fatal stabbing. No murder charges have been laid.
Mr Venditto said police believed the fatal altercation was linked to Operation Meld, a crackdown targeting youth gangs.
"The theory at the moment is that this is an incident between two groups that know each other," he told reporters.
"The threat to the public is there because they've got bladed weapons and other weapons and react with spontaneous acts of violence ... 13 violent people are now in custody."
He said police resources have already been increased in the city centre and community leaders were working with investigators to bring the gang problem to an end.
Two cars were seized overnight after police searched a blue Holden and found two knives, a machete and cash.
A silver Holden was also seized after police found a knife in the back seat.
All 13 men were refused bail or did not apply for bail and will appear in the Adelaide Magistrates Court on Tuesday.
Police also arrested seven people aged 16 to 25 on unrelated matters, including several in connection with an assault at Nairobi Affair Lounge on March 13.
A 19-year-old from Werribee in Victoria was charged with carrying an offensive weapon.