Police have laid murder charges after earlier arresting seven people in relation to the deaths of two boys aged 12 and 15 in Melbourne's outer west.
Dau Akueng, 15, and 12-year-old Chol Achiek were killed on their way home from basketball in the suburb of Cobblebank earlier this month.
Authorities at the time described the scene as "one of the worst" knife crimes they had seen.
Homicide Squad detectives today arrested three men and four teenage boys as part of their investigation.
Warrants were executed at about a dozen properties across Melbourne's outer west and north at 6am this morning with assistance of the VIPER youth gang taskforce.
A 19-year-old Thornhill man, two 16-year-old boys and a 15-year-old boy have been charged with the murder of 15-year-old Dau Akueng.
A 19-year-old Caroline Springs man, an 18-year-old Wollert man and a 16-year-old boy have been charged with the murder of 12-year-old Chol Achiek.
Prince Conteh, Peter Addo and Abel Sorzor have faced the Melbourne Magistrates' Court, with no applications for bail made.
The matter is due to return to the court in December.
Emergency services were called to Marble Drive just before 8pm on Saturday, September 6 where they found 12-year-old Chol Achiek with critical injuries.
Police found 15-year-old Dau Akueng seriously injured a short time later on nearby Cobble Street.
Members of the public performed first aid on both children but they died before they could be taken to hospital.
Victoria Police said the incident prompted a significant investigation led by homicide detectives, as well as increased patrols in the Cobblebank area and meetings with local leaders.
Assistant Commissioner Martin O'Brien said the investigation had been exhaustive and complex.
"The word senseless has been used so many times already in relation to the deaths of Dau Akueng and Chol Achiek, because the reality is that it doesn't make sense," he said in a statement released on Friday.
"Two children walking home after playing sport, who should have had decades of their lives ahead of them.
"Instead, their devastated families are grieving their loss and all the things they will never get to see two children grow up to achieve and experience."
Assistant Commissioner O'Brien said the deaths were of concern to police as well as the community.
"I know many people will be feeling shocked, frustrated and concerned in light of this matter," he said.
"I want to reassure you that locally, police will have increased patrols in the area and are working closely with community groups.
"Finally, our thoughts are with the Akueng and Achiek families and we will continue to ensure all available support services remain in place at this difficult time."
Coach says young teammates 'angry' over loss of Dau
Dau Akueng grew up in the flats around Collingwood and Fitzroy before his family moved to Melton in Melbourne's outer west, according to a GoFundMe set up following his death.
His mentors have remembered him as a talented and dedicated basketballer.
He dreamed of playing college basketball in the United States or the NBL at home in Australia.
Online records list him as a player in two games at Cobblebank Stadium on September 6.
Former Collingwood All Stars coach Karl Morrell said the basketball community was still mourning the loss of Dau, a popular leader.
"The boys who were quite close to Dau, and part of the basketball team that I was associated with, I've been keeping in close contact with them," he said.
"They're very angry. They're angry, they're disappointed, and they don't feel safe — especially the parents."
Mr Morell said he was concerned about how Dau's death would affect his former teammates as time went on.
"What I'm really concerned about is the next few weeks when people aren't there, people aren't showing as much compassion and caring as the first initial few weeks and being a support network," he said.
Chol Achiek was killed after getting off the same bus as Dau Akueng as they both returned from the Cobblebank basketball stadium.
His father was one of the speakers at a candlelit vigil attended by a large crowd in Melton last week.
Those gathered were told 12-year-old was intelligent, caring and always laughing.
Chair of South Sudanese Community Association, Andrew Ohide, said locals were still trying to heal.
"The news [of the boys' deaths] was shocking and even now many people are not able to comprehend it," he told ABC Radio Melbourne.
"We're still in the situation of we're mourning.
"We're just waiting to bury our children to rest with dignity."
He said funerals for the boys would be be held late next week.
