The grandfather of a 17-year-old boy who died trying to cross the Swan River in Perth while fleeing police says his grandson was a happy child who fell in with the wrong crowd when he moved to the city from a small country town.

Key points: Family members are mourning two teenage boys who died after entering in the Swan River

Family members are mourning two teenage boys who died after entering in the Swan River They were part of a group of five teens fleeing police in the suburb of Maylands

They were part of a group of five teens fleeing police in the suburb of Maylands An Indigenous leader says he is disgusted by vitriol posted about the boys on social media

Two teenagers died while trying to cross the river in the suburb of Maylands on Monday, after trying to escape police.

A neighbour had seen a group of teenagers jumping fences following reports of a burglary in the area and flagged down a police patrol car, before two officers gave chase to five boys, four of whom ran into the river.

A memorial has been erected at the river near where the boys died. ( ABC News: David Weber )

One boy made it almost all the way across the river and was met by an officer, and another was brought out of the shallows on the opposite bank.

But two boys got into trouble in the middle of the river.

The body of one boy was recovered on Monday night and another was found on Tuesday morning.

A country boy constrained by the city

Roderick Simpson, who requested his grandson's image and name not be used for cultural reasons, said the boy was happy when living with family in the small Wheatbelt town of Mullewa, about 450 kilometres north-east of Perth.

"He loved motorbikes, motorbikes was something that he really, really wanted to master," Mr Simpson said.

"Living in Perth just didn't give him that space to get out on the bike and ride it until it couldn't be ridden no more.

"Being in Perth he just didn't have that space. He's a country boy."

Mr Simpson said his grandson played football in Perth and Mullewa, but his attendance became patchy and he started mixing with the wrong people.

"You know, we can't pick our kids' friends. It's very difficult," he said.

"We found it a bit hard … we just couldn't keep up with these young people.

"We're pretty much country people. There, we take kids to the police station and hand them over. In Perth you can't do that, it's not that simple."

Sorry, this video has expired Vision shows dramatic rescue of two boys before search launched for three others

Father pleads with people not to judge

Christopher Drage, the father of the other boy who drowned in the river, said the teens were scared and made a fatal error of judgment.

"He was a good boy, I guess he just made a fatal decision to jump in the river to get away from police," he said.

"Obviously they were scared, they were only young boys.

"I ask people not to be judgemental, and I think we all made silly mistakes as kids, it's just tragic that they lost their lives."

Mr Drage said his son was a good sportsman, a good motorbike rider and loved by all his family.

The extensive river search continued until a fifth boy was confirmed safe. ( ABC News: James Carmody )

He said the shock of the event was still sinking in, but he was not rushing to blame the police for the incident.

"I'm a bit numb at the moment," he said.

"A lot of people want to blame other people or whatever, upbringing or the police. But I suppose these young boys, that's their way of having fun and unfortunately it costed them their lives.

"The boys chose to do what they'd done, I suppose they didn't realise the extent of what it was going to cost them.

"Value your life, and realise that it could be here one minute and gone the next."

We don't know the facts: grandfather

Mr Simpson said it was hard to know exactly what had happened during the police chase.

Mounted police took part in the search for the missing boys after the chase ended in tragedy. ( ABC News: James Carmody )

"With the police, we all understand they have to do their jobs, [but] whether it's all coordinated in the right manner is pretty much the dark side of the police work," he said.

"If it's coordinated, planned correctly, there shouldn't be any backlash. But it's just difficult at times not knowing the facts about what's going on.

"We do know that when kids get on the run, they take risks.

"We just hope that there wasn't … [they weren't] forced into a risk that they shouldn't have been taking."

Police divers recovered one boy's body on Monday before a second was found yesterday. ( ABC News: James Carmody )

Teenager praised by football club

One of the boys had played for the Mullewa Football Club and president Mick Wall said the death of one of its own had hit the club pretty hard.

Mullewa Football Club president Mick Wall says the boy was growing both as a footballer and a person. ( ABC Geraldton: Glenn Barndon )

"With our club half the people are related or in-laws somehow, and when something goes wrong we all hurt," Mr Wall said.

"We've struggled to get our colts to go training for the last few years, but this year they were there all the time, and he was part of that.

"He'd say 'come on boys, let's go to training'. He was just sort of a leader.

"He was just getting better and better, not only as a footballer, as a person. He was doing great."

Spectre of deaths in custody looms

In the wake of the fatal chase, Indigenous Senator Patrick Dodson said WA's long history of Indigenous deaths in police custody would be in the minds of community members.

Patrick Dodson says there are many unanswered questions after the deaths of the boys. ( ABC News: Adam Kennedy )

"A couple of sad things have happened in our state. Miss Dhu dying in custody, Mr Ward dying in the back of a van, and that young man [Elijah Doughty] out at Kalgoorlie," he said.

"These things add up and they become part of the community collective consciousness, and often it's very difficult to distinguish a particular set of facts in a particular circumstance from a generality of how policing services and the justice system operates."

Police rescue one of the boys from the Swan River in Maylands. ( Supplied )

Senator Dodson said the recent deaths would also cause distress in the wider WA community, which was still reeling from the discovery on Sunday of the mass murder of a family including very young children in the Perth suburb of Bedford.

"I know that many people are hurting and are sad and sorry, and often that can transfer into anger, but we haven't got all the facts and we don't know what the situations were at the time," Senator Dodson said.

"We have to ask ourselves though, what is it about the community life of these young men that caused them to come before the attention of the police?

"And really, what is it about the fear of police that causes young people to take risks that put themselves in harm, and other people [including] police themselves?"

Senator Dodson said he hoped an investigation into the deaths also looked into the effectiveness of current policies for pursuits.

Social media attacks condemned

Indigenous and non-Indigenous community members also raised concerns about the level of vitriol displayed on social media after the boys' deaths.

Aboriginal Legal Service of WA chief executive Dennis Eggington said some of the comments were "inhuman".

Dennis Eggington says the deaths should not become an excuse to wage war on social media. ( ABC News: David Weber )

"I was shown a couple and I refused to even continue to look at it …," he said.

"If you could imagine the most vile, inhuman, nasty, horrible types of comments then you'll be getting close to what I saw.

"It surprises me, it's got to stop. This country has got to do something about this underlying hatred.

"It's just such a tragedy and that's the way it should be seen, not as an excuse to go to war with one another."

WA Police Commissioner Chris Dawson said he had spoken to Mr Eggington about the problem and warned social media users to exercise caution.

"We have a shared concern that people should really temper and measure any comments on social media, because if they're not going to be helpful and supportive, don't put them on there," he said.

Same police station dealt with two tragedies

Commissioner Dawson revealed the police officers involved in Monday's incident were from the same station that dealt with the mass murder crime scene at the Bedford house.

"It's always been difficult, and I've found this personally myself, when you are attending to matters which involve the loss of young lives," he said.

"Any loss of life of course is tragic. But I know it affected me, and it affects every officer that has to deal with it, with younger people and infants involved. They are particularly difficult situations to deal with."

Police say help is being made available to officers who attended the Bedford and Maylands tragedies. ( AAP: Richard Wainwright )

Commissioner Dawson said help was being made available to officers.

The drownings were being considered as deaths in police presence — the same as a death in custody.

"While we didn't have direct physical contact with the boys that have succumbed, we were in a foot chase with them before they entered into the river, so that does require us to treat it exactly the same," Commissioner Dawson said.

Mr Eggington called on police to speed up the coronial inquest process where possible.

"Misinformation is quite damaging … coronial inquests are notoriously long in this state, it can take years," he said.

"It's in the best interest of our community to put extra resources in."