The officer, who can’t be named, became visibly distressed and emotional as he told the hearing about his desperate attempts to save the two teenage boys.
The TRG officers happened upon the scene by chance in the Perth suburb of Maylands not far from the riverbank.
16 year old Christopher Drage and 17 year old Trisjack Simpson Ninyette drowned in September 2018 when they attempted to run from police after trespassing and a burglary in suburban Perth.
Two officers pursued the group on foot with one boy splitting off while the four boys ran towards the river in an attempt to evade police.
Swan River: 'Worst I'd seen it'
The officer who can only be referred to as operator 65 described how he rushed into the cold river during the most challenging conditions he has seen.
"It was very choppy and cold, with white water caps," Operator 65 told the inquest.
"It appeared the current was very strong, down river and the wind was blowing up river which caused the choppiness and terrible conditions," the TRG officer said.
The officer who had almost 30 years policing experience became emotional as he tearfully told the court how he saw the boys clearly struggling and tried to reach them.
"I swam towards that person that was about 30 or 40 metres - I was saying 'get on your back mate, try and float' but he went down," Operator 65 told the inquest.
"I swam towards that person that was about 30 or 40 metres - I was saying 'get on your back mate, try and float' but he went down," he told the inquest.
"I was unable to do anything... the next person was still struggling - I determined that was where i needed to go and as a result i needed to save that person," he said.
Concerns over junior police officers partnering together
The specialist TRG officers are highly trained with far more rigour than uniformed officers the inquest was told with concerns being raised over training and rescue policies and partnering junior officers with less experienced police officers.
WA Police Detective Sergeant Roy Begg told the Coroner that conditions were extremely challenging and he didn't fault the police officers for not entering the water to attempt to save the boys.
Mr Begg was the investigating officer brought into oversee the investigation and wrote the report for the coroner, the officer paid tribute to the officers.
"The actions of the TRG were extremely brave to enter the water, it was very dangerous," Mr Begg said.
Operator 65 told the court that when he reached the surviving boy, he told the officer he and the boys had committed a burglary.
The officer become emotional as he said the 15 year old teenager was clearly distressed, in shock and crying out that he loved them.
"I was trying to calm him down - He was in shock. I tried to divert talked about football, talking about Fremantle to try and calm him." he said.
He told the court he believed that there was nothing else the attending uniformed officers could have done due to the dangerous conditions of the river.
The TRG officers who responded both received bravery commendations for their actions on 10 September 2018 with the families of both boys thanking them in the court on Wednesday.
WA's police force is under scrutiny over the incident with policies and training also being examined by the coroner, yesterday the court heard one attending officer was just 20 years old at the time and still a probationary officer while the second officer had only been off his probationary period for about five months.