Two teenage Aboriginal boys have drowned in Perth's Swan River after diving in to evade police.
As police pursued five boys on foot following reports of teenagers jumping fences in suburban Maylands on Monday afternoon, four of them jumped into the water.
Police captured two, but the other two were spotted struggling in deep and murky water in the middle of the river.
Commissioner Chris Dawson said officers swam out in a bid to rescue them but were unable to reach them before they went under.
"Police did not physically come into contact with the two boys who disappeared under water in the middle of the river," Mr Dawson told reporters on Tuesday.
The first body was recovered in extremely low visibility at 8.30pm on Monday and the second was discovered just before 10am on Tuesday.
A coroner will hold an inquest into the deaths, assisted by the major crime division, internal affairs unit and coronial investigations unit, because police were present.
Mr Dawson said the fatalities would be treated with the same seriousness as a death in custody.
"Whether a person is actually in custody or a loss of life occurs in our presence, they're treated exactly the same way," he said.
Aboriginal Legal Service chief executive Dennis Eggington urged the state government to put extra resources into the investigation to give answers to the families.
"Anyone who knows our community will note that the vast majority of the Noongar community today will be in mourning," Mr Eggington told the ABC.
"I haven't seen this level of grief, bordering on anger, but certainly grief and pain for a long, long time."
He said the boys would have been "absolutely in terror, running frightened and hitting the river, and being in more trouble and being more frightened", while the survivors would be "scarred for the rest of their lives".
Aboriginal activist Herbert Bropho told the Nine Network he held police responsible for the deaths.
Mr Dawson said the deaths were "nothing short of a tragedy".
"The loss of any young life is an absolute tragedy," he said.
There were fears the fifth teen in the group, who was last seen running along the riverbank, had also jumped in, but he was found safe on Tuesday afternoon.
"He is now with family members," police said in a brief statement.
While the desperate search for him was underway, Mr Dawson said the surviving pair had not been charged with any offences.
"Any matters concerning offending need to be put squarely to one side," he said.
The commissioner called on members of the public to provide any information or CCTV footage that may aid the investigation.
Police said all of the boys were under 18 and declined to release more details at the request of their families.
Australian Associated Press