Let's bring you some more detail from Supt Owain Llewellyn from North Wales Police, who says that one 16-year-old, two boys aged 17, and one 18-year-old were found in the overturned car near Tremadog.

He adds police are not in a position to confirm the identities of the teenagers at this stage.

"Clearly it wasn't the outcome we were hoping for," he says.

Liz Saville Roberts, MP for the area, and Mabon ap Gwynfor, Senedd member, have released a statement thanking the emergency services.

"This news is truly heartbreaking and foremost as parents ourselves, our thoughts go out to the families and friends of the four young men whose lives have been lost in this tragic accident," they say.

"We would like to pay tribute to the emergency services and local mountain rescue teams involved in the search operation, and to members of the public for their assistance in helping to locate the vehicle.

"No words can sufficiently reflect the sorrow that this news brings to our whole community."

Supt Owain Llewellyn says police investigations into the circumstances of the incident are ongoing.

"I would like to take this opportunity to publicly thank the emergency services and members of the voluntary search agencies and members of the public who supported us with this search," he says.

"And finally, I would ask the families of these boys are afforded privacy at this desperate time."

More from the North Wales Police update now.

Supt Owain Llewellyn says officers came across a Ford Fiesta overturned and partially submerged in water.

He says that tragically the bodies of four young men were recovered from within the car, adding that their families have been informed.

"Whilst the search is concluded, there is an ongoing investigation to formally identify those within the vehicle and to understand what has led to this tragic incident," he adds.

Now we've head from North Wales Police, here's an at-a-glance summary of what we've just learned:

• The bodies of four missing teenagers have been found in north Wales
• Officers said they appear to have died in a "tragic accident" after the car they were travelling in seems to have left the road on the A4085 near Garreg, Gwynedd
• Investigations into the deaths are ongoing, the force also confirmed
• The silver Ford Fiesta was found after police were contacted by a member of the public, police confirmed earlier

• Jevon Hirst, Harvey Owen, Wilf Henderson and Hugo Morris, from Shrewsbury, Shropshire, have been missing since Sunday morning

North Wales Police says the incident "appears to have been a tragic accident" at the moment, in its update saying four bodies have been found in a car that appears to have left the road.

Supt Owain Llewellyn says the force's "thoughts are with the family and friends of the four young men at this very difficult time".

He says there has been "extensive search" by several different emergency response agencies and volunteers, adding that "this is sadly not the outcome that any of us would have wanted".

"We would ask that the family be afforded the appropriate privacy and respect," Llewelyn says.

Investigations are ongoing to establish the circumstances of their deaths, he adds.

Four bodies have been found in the search for the missing teenagers, North Wales Police says.

We're expecting North Wales Police to issue an update to the media on what they've found at about 16:30.

It will be a statement only and there won't be any questions, but we'll update you with all the key lines here.

Councillor June Jones, who represents the Llanfrothen area on Gwynedd's council - Cyngor Gwynedd - says the community is in "complete shock".

"It's been a tremendous few hours really... the thoughts of the whole valley are with the families of these young lads."

North Wales Police says a statement will be read to the media by Supt Owain Llewelyn at 16:30 GMT today at its headquarters in St Asaph.

But no questions will be taken today, it says.

Image source, Google

Meole Brace School in Shrewsbury, where all four teenagers previously attended, says it is "fully supportive" of emergency service efforts to find the boys.

"Jev, Harvey and Wilf left us last year at the end of Year 11, and Hugo the year before. All four boys were well-thought [of] and well-known by the school community," its head teacher Alan Doust says in a statement.

"Our thoughts and prayers are with them and their families for their safe return."

Meanwhile, Shrewsbury College has confirmed all four boys are students there, studying for their A-levels.

"The college’s immediate thoughts are with the family and friends of the teenagers missing.

"This is a very worrying time, and we all want them to be found safe and well," it says.

Gareth Pritchard, former deputy chief constable of North Wales Police and trustee of the Ogwen Montain Rescue Team charity, says locating the teenagers is the biggest challenge facing the emergency services.

Speaking on BBC Radio Cymru's Dros Ginio programme, he said: "It is such a vast area and not knowing the route of the teenagers will make it even more challenging and will take a lot of time."

He says the community's knowledge and help is essential in the attempts to locate the the teenagers.

If you've just joined us, here's what's happened so far.

• A car in which four missing teenagers were travelling has been found
• Police said it was discovered following information from a member of the public
• Jevon Hirst, Harvey Owen, Wilf Henderson and Hugo Morris, believed to be from Shrewsbury, Shropshire, have been missing since Sunday morning
• A police cordon has been set up on the A4085 between Garreg and Pont Aberglaslyn and the road is closed
• An air ambulance was seen in the area and two ambulance service vehicles have driven through the cordon near the villages of Garreg and Llanfrothen

Stay with us as we bring you the latest developments.

A forensics van has been seen on the road near where the car was discovered earlier.

We'll bring you more information as we get it.

Phil Mackie
Reporting from the scene

It's a particularly windy, narrow, steep road and these are people who've only recently passed their driving test.

Within the past hour, we know that the silver Ford Fiesta in which they were travelling has been recovered further up that road.

We also know that an air ambulance was seen in this area a little time before that.

In the past few minutes two Wales ambulance service vehicles have driven through the police cordon near the villages of Garreg and Llanfrothen, according to Brendon Williams, one of our reporters at the scene.

The cordon's been set up on the A4085 between Garreg and Pont Aberglaslyn and the road is closed.

Emyr Owen, who lives nearby, spoke to our reporter, Matthew Richards.

"I was woken about 5am by the sound of the helicopter above, so I got up to look through the window.

"The policeman told us all he'd had the orders to close the road - you can't go through there towards Beddgelert.

"It was atrocious weather on Sunday. I don't know what happened to four young men in the car, hopefully nothing bad."

The silver Ford Fiesta the teenagers were travelling in was found near Garreg, Gwynedd, police say.

Footage from the scene shows a police presence in the area.