A black Audi A3 went into the water in Sunderland on Tuesday afternoon, killing two boys and a girl, Northumbria Police said.
Four people are understood to have been in the car at the time. Following a major emergency operation, the three bodies were recovered from the water.
The search centred on the area around Panns Bank, near Wearmouth Bridge, where the car entered the water around 1.30pm on Tuesday.
A 17-year-old boy who managed to reach safety has since been arrested, the force said. He is in hospital with non-serious injuries, and remains in police custody.
Chief Superintendent Scott Cowie, area commander for Sunderland, said: "This is a truly tragic incident where three young people have lost their lives.
"Our thoughts are with their families, friends and all those impacted by what has happened.
"We will continue to support them in any way that we can, and ask that their privacy is respected at this time."
He added: "Our investigation is at a very early stage in establishing the circumstances surrounding what has happened.
"We would ask members of the public not to speculate about the incident, both on social media and in the community.
"In doing so, please be mindful of the potential impact such commentary could have on the families of those involved in this incident."
Northumbria Police have asked members of the community to avoid the area.
Earlier this afternoon, police, ambulance crews, the Royal National Lifeboat Institution and the Coastguard were on the scene.
The Tyne and Wear Fire and Rescue Service also sent two fire engines and a boat to assist with the rescue operation.
In a post on X, Lewis Atkinson, Labour MP for Sunderland Central, said: "I'm aware of the serious incident in the Wear this afternoon. My thoughts are with everyone involved and their families, and with the emergency services responding to the scene."
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Kim McGuinness, mayor for the North East, said: "I'm aware of the serious incident on the River Wear today after a car entered the water in Sunderland.
"Rescue teams are at the scene and right now we must hope and pray for those involved."
An investigation into the head-on collision on the A66 near Middlesbrough last month found no evidence of deliberate contact, or the use of a stinger, before the crash, the Independent Office for Police Conduct (IOPC) said.
The crash between a Volkswagen Passat and a marked Cleveland Police vehicle happened at South Bank at 3.39am on 22 August, and followed a police pursuit which was abandoned.
PC Matthew Blades and PC Tom Clough, who had not been following the Passat, were killed in the collision
Michael Cahill, Theo Rae, Cole Worthy, Jakub Matusiak and Makai Saddington were in the VW.
According to the IOPC, the pursuit began at 3.33am, and, six minutes later, the Passat slowed as it approached the A66 and headed the wrong way down the dual carriageway.
The pursuing police driver did not follow the Passat along the wrong carriageway, and instead drove along the A66 on the right side of the road, the IOPC said.
Both cars collided around 17 seconds later, and there was no evidence the police initiated contact, the body added.
IOPC Director of Engagement Emily Barry said: "It's important to acknowledge that due to the vast amount of information to be reviewed, analysed and verified, along with the expert reports that have been commissioned to support our investigation, we anticipate it will take months, rather than weeks, to conclude our investigation.
"We have ensured that all families have been made aware of our involvement and they will be provided with regular updates throughout.
"We are aware there is speculation regarding how the collision occurred. There is no suggestion the collision was a result of any direct police contact, nor was a stinger used by the police in an attempt to stop the Passat."
The IOPC has commissioned two reports, one of which will analyse a reconstruction of the collision. The other will assess policies and procedures which are currently in place for police officers during pursuits.
A forensic collision investigator is still determining the speed of both vehicles at the time of the collision.
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Cleveland Police previously said the Passat had been pursued after a house in the Acklam area of Middlesbrough was rammed by another vehicle.
The force also previously stated that the five men in the Passat may have had links to "serious and organised criminal activity", and four of them had previous convictions.
Merseyside Fire and Rescue Service (MFRS) said the lithium-ion battery was not inside the scooter at the time and is believed to have been on charge when the fatal fire started.
The blaze broke out at the home of Elisha Brabin, 36, in Bootle, Merseyside, last Tuesday, killing her children Leo, 16, Ellis, 8, and seven-year-old Prudence.
On Monday, the MFRS said an electrical fault caused the battery to go into thermal runaway, which occurs when the battery generates more heat than it can safely release, causing its temperature to rise dangerously.
Ms Brabin and her children were found in an upstairs bedroom by firefighters who were called to the home at about 3.45am.
Another person was taken to hospital suffering from burns.
Kev Johnson, head of prevention at MFRS, said: "I would like to commend the efforts of our fire control staff and our fire crews, also working with NWAS colleagues, who made every effort to provide a different outcome, but sadly this was not the case due to the speed and intensity of the fire.
"This tragedy highlights the very real risks posed by lithium-ion batteries, which we confirmed as the source of the fire."
The MFRS said there had been 150 fires linked to lithium-ion batteries in Merseyside between April 2023 and August 2026, and five fatalities linked to the batteries.
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Mr Johnson added: "We're urging people to follow the manufacturer's instructions, only using batteries and chargers which have been supplied with the vehicle or approved by the manufacturer, as anything else can pose a huge fire risk.
"It's also important to know and recognise the signs that your lithium-ion battery may be failing - if it is swelling, making unusual sounds, has a strong smell, is failing to charge, or is smoking, please stop using immediately."
Following their deaths, the family of Ms Brabin said she was a "devoted and loving mother who lived for her children".
They said: "The tragic loss of Elisha and our three precious children has left us heartbroken. They have all been taken from us far too soon.
"The loss we are experiencing is unimaginable, and the impact on our family will be felt forever."
Dr James Cotton, executive medical director for the health board, said Sam Eljamel "could and should have" been struck off years before his resignation, which he offered voluntarily rather than facing a medical tribunal.
Speaking before the Eljamel Inquiry on Tuesday, Dr Cotton told senior counsel Jamie Dawson KC that he would have personally stopped the surgeon from practising long before he resigned after a number of concerns were raised, leading to him being placed under supervision in June 2013.
Mr Dawson asked if something had gone wrong with Eljamel's supervision requirements, with Dr Cotton replying: "Fundamentally, yes."
The inquiry heard that the supervision Eljamel was placed under involved weekly meetings where he discussed his patients but did not address his practise in itself.
Dr Cotton said: "The evidence that I've got, I cannot understand why he was allowed to continue to operate alone, or [was allowed to operate] at all. I cannot understand that."
He added: "I think a proper risk assessment should have taken place, and whether he needed direct supervision of his surgical practise, as in one-to-one supervision, or not operate at all, or suspended, and that would require probably some subject matter expertise at the time.
"But I can say to you, as medical director, that's the decision-making process I would be starting to think about when I read those concerns."
Mr Dawson interjected: "But I think you said a moment ago that he should not have been allowed to operate. Is that right?"
Dr Cotton replied: "Yes, I don't think he should have been. I think if I was to make that decision today, I would not let him operate."
The inquiry then heard how a fellow medical practitioner made a complaint against Eljamel in December 2012 to the chief executive of NHS Tayside, alleging a botched sight surgery.
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Another sight surgery complaint was made back in 2007, and Mr Dawson pressed Dr Cotton as to whether these examples, along with the many other allegations of malpractice over the years, should have led to Eljamel being struck off.
Dr Cotton said: "It could and should have happened, yes."
The panel also heard how Dr Cotton denied there was any form of cover-up into Eljamel's actions throughout the years.
Eljamel was a consultant neurosurgeon at Ninewells Hospital in Dundee from 1995 until his suspension in December 2013.
During that time he is thought to have harmed as many as 200 people and left some with life-changing injuries.
Eljamel resigned from his post in May 2014, removed himself from the general medical register the following year, and is now believed to be operating in Libya.
The inquiry, taking place before Lord Weir in Edinburgh, continues.
Ksenia Maximova, who was born in Russia, says Moscow is "constantly probing all the defences" of the UK and its allies.
The former model is a serving Lib Dem councillor on Ealing Borough Council and is founder of the Russian Democratic Society, an organisation designated as "undesirable" under Russian law.
She told Sky News being put on Russia's list of terrorists is not a surprise.
"For years everyone was saying it's a bit random that I was still not on it," she added. "I guess I'm one of the last ones, I was a bit more careful."
Russian authorities have opened a case against Ms Maximova under Part 2 of Article 205.5 of the Russian Criminal Code, which concerns participation in an organisation designated as terrorist under Russian law.
Ms Maximova started the Russian Democratic Society, which works to counter authoritarianism and war by empowering democratic voices from Russia.
Russia added the group to its list of undesirable organisations earlier this month.
Ms Maximova could face prosecution if she returned to Russia, but told Sky News that she already knew she could not go back.
"The problem comes if they stick you on Interpol," she added, saying that could see her held up at passport controls when she travels.
The FSB, Russia's main spy agency, claims Britain wants to bring together Russian opposition to create the illusion of an alternative to replace the government in Moscow, the Russian state-owned TASS news service reports.
The agency claims it knows the identities of all emigres who have decided to work with London and wish to see Russia defeated.
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Ms Maximova insisted that she is determined to continue with her anti-war activism.
"If someone decides to get rid of me, they just will, there's nothing I can really do about that," she said.
She previously told Sky News how she had to brief her children on what nerve agent exposure looks like following the Salisbury poisonings.
Asked about the alleged hybrid attacks across the continent that European capitals have blamed on Russia, Ms Maximova says not enough is being done.
"Russia is constantly probing all the defences of every single country and the fact is that if they did want to do some damage they could quite easily," she added.
It comes as defence secretary Wes Streeting said the UK needs to have a national conversation around war preparedness.
He told Sky News Defence Insider that the threat from Russia is real and urged for greater resilience in the UK.