Victoria's outgoing police chief admits tackling knife crime is proving a challenge, after two security guards were stabbed at a suburban shopping centre and two teens were killed in the past 10 days.
Chief Commissioner Graham Ashton said knife crime among youth gangs is a problem all over the world, including cities like London, as most people have easy access to knives at home.
"It's really hard to regulate knives," he told 3AW radio on Thursday.
"Knives can be found in any home and any knife can be lethal, so it is a challenge in dealing with knife crime, and as I say around the world people have been grappling with it for some time."
Data released by the Crime Statistics Agency last week found knife crime among gangs has increased by almost 40 per cent during the past five years.
Mr Ashton's comments come after two security guards were stabbed at Westfield Fountain Gate on Wednesday night.
Police were called to the Narre Warren shopping centre just before 6pm following reports the guards were involved in an altercation with a woman and a man.
The woman, aged 34, allegedly lunged at one of the security guards, slashing his shirt.
The man, 39, was tackled to the ground by another customer while the woman allegedly continued to threaten staff and other people in the store.
The woman is under police guard in hospital, while the man is expected to face Dandenong Magistrates Court on Thursday charged with theft, weapon offences and committing an indictable offence while on bail.
Just days earlier, 21-year-old Machar Kot was stabbed outside a hotel in Melbourne's CBD and later died in hospital. His alleged killer Marco Deng remains on the run.
Fifteen-year-old Solomone Taufeulungaki was also stabbed to death outside a Deer Park shopping centre on June 16.
He was allegedly approached by a group of 10 youths armed with knives.