At least 40 were killed and a further 119 were injured in the blaze that swept through the Constellation bar in Crans-Montana in the early hours of New Year's Day.
Read more: Everything we know about ski resort fire
A former Hertfordshire schoolgirl is among the teenagers still missing.
The severity of burns is making it harder to identify the dead and injured. Experts are relying on DNA samples for some cases, in a process that could take weeks.
Scrutiny turns to safety set-up and fire's cause
On Friday officials tentatively confirmed a theory circulating online about the cause of the fire.
"It would appear that the fire started from sparkler candles, otherwise known as flares, which were placed on top of champagne bottles," Valais attorney general Beatrice Pilloud told a news conference.
Images shared on social media showed a group of people with sparklers affixed to bottles that appear to be setting fire to the ceiling, and a woman on a man's shoulders holding up champagne bottles with sparklers in them.
But Ms Pilloud said it was too soon to say whether a foam-like material on the ceiling, possibly sound-proofing, had contributed to the spread of the fire.
A retired fire firefighter told Sky News the same type of material used to clad Grenfell Tower was likely coating the ceiling of the basement bar.
Having reviewed images and videos circulating online, Steve Dudney said he believed the foam that ignited was highly flammable polyurethane, which should be "nowhere where there are uncontrolled naked flames".
Ms Pilloud said the bar's owners, Jacques and Jessica Moretti, a French couple, were interviewed as "people called to give information", not under caution.
There are many outstanding questions about the nature of exits and about safety protocols in the bar. It had more than one emergency exit, but it wasn't found by victims.
Agonising wait for families
The severity of the damage means details about the victims have emerged in instalments, leaving relatives in a painstaking limbo.
Some 22 young patients are in critical condition at Lausanne University Hospital.
The injured included 71 from Switzerland, 14 French nationals and 11 Italians, along with citizens of Serbia, Bosnia-Herzegovina, Luxembourg, Belgium, Portugal and Poland, according to Frederic Gisler, police commander of the Valais region.
The nationalities of 14 people were unclear.
Who has been named so far?
Those still unaccounted for include Charlotte Niddam, who previously attended Immanuel College, a private school in Hertfordshire. Her nationality has not been confirmed.
According to the Crans-Montana resort website, she had been working as a babysitter in the area.
Italian national Emanuele Galeppini, 17 and a golf prodigy, was the first victim to be reported dead, with news confirmed by the Italian Golf Federation earlier on Friday.
Another teenager who is still missing is Arthur Brodard. CNN reported that the Swiss 16-year-old joined around 10 of his friends on New Year's Eve at Le Constellation.
His parents Laetitia Brodard and her husband Christophe, who are from the Swiss city of Lausanne, said the group often met in the resort town.
"We are so empty," Mr Brodard said. "We think he could still be alive, so we still have hope of finding him."
He added: "They ordered a bottle of champagne with a sparkler. One or two minutes later, it was the apocalypse."
Alice Kallergis, a 15-year-old girl from Greece, is also reportedly missing. Her brother, Romain, told protothema.gr: "We still know nothing about my sister."
The family of another young person has appealed for information.
Emilie Pralong has been missing since the fire, according to posts on Facebook.
A number of weather warnings for snow and ice have been issued by the Met Office, with multiple yellow alerts extended into Monday.
In north Scotland, amber snow warnings are in place until midday on Saturday.
On Saturday and Monday, the east coast of England is expected to be hit by blizzardy conditions.
At Loch Glascarnoch in the Scottish Highlands there was in excess of 8cm of lying snow on Friday morning, while Aboyne in Aberdeenshire had around 9cm of lying snow.
The chilly conditions have led to the closure of several snow gates, stopping travel on some roads.
Traffic Scotland said the snow gates on the A93 Braemar-Glenshee, A939 Tomintoul-Cockbridge, B974 Cairn O'Mount-Fettercairn and at Bealach na Ba were shut on Friday morning.
Highland Council said it had received reports of campervans and cars stuck on ice in tourist hotspots. It has advised motorists to drive with caution.
The areas covered in the amber warnings include Angus, Perth and Kinross, Aberdeen, Aberdeenshire, Moray, and the Highlands.
Around 10-20cm of snow is likely at low levels, with 30-40cm possible on higher ground, while winds could lead to temporary blizzard conditions, according to the Met Office.
The weather is expected to have an impact on transport, with those heading out urged to prepare for longer journey times by road.
Some delays and cancellations to rail and air travel are likely, as are power cuts, according to the Met Office.
Chief Superintendent Scott McCarren, Police Scotland's head of road policing, said: "Please don't drive through road closures, the decision to close roads is not taken lightly and is done for public safety."
Parts of England also saw a blanket of snow as 2026 got off to a wintry start.
A yellow weather alert for snow and ice is in place across most of Wales, while a yellow warning for ice in the southwest of England was issued by the Met Office on Friday morning.
A yellow weather alert for much of Northern Ireland starts at 3pm on Friday, with the country warned to expect snow and ice until midday on Monday.
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Met Office chief meteorologist Rebekah Hicks said: "Arctic air and brisk northerly winds are gripping the UK as we start the new year.
"Snow and ice warnings remain in force for many areas, with the risk of heavy snow showers, especially across northern Scotland and over higher ground elsewhere, though many inland areas will stay largely sunny and clear.
"Bitterly cold conditions will persist through the weekend and into next week, with daytime temperatures struggling to rise above freezing for some, and overnight lows dipping to minus double figures in places.
"We urge people to stay #WeatherAware, keep up to date with the forecasts and plan ahead as icy roads and slippery surfaces are likely."
Meanwhile, the UK Health Security Agency (UKHSA) has issued amber warnings which will remain in place until 10am on 9 January.
The alert has been issued for the East Midlands, West Midlands, North East, North West, South East, South West, East of England, Yorkshire and the Humber, and London.
The UKHSA said it means the weather is "likely" to cause significant impacts across health and social care services, including a "rise in deaths" among those with health conditions or aged 65 or over.
Officials were first alerted to reports of people in trouble near Withernsea at 3.10pm on Friday. A 67-year-old man was found unconscious in the water and later confirmed to have died.
Late on Friday evening, Humberside police said a second body was recovered from the sea and added that "circumstances are not believed to be suspicious."
Searches are ongoing, and one person is still thought to be missing.
The force asked people to avoid the area to allow the emergency services to carry out their work.
HM Coastguard said it had deployed a search and rescue helicopter and a fixed-wing aircraft to the scene on England's east coast.
The rescue operation has also called in local coastguard and RNLI (Royal National Lifeboat Institution) rescue teams, Yorkshire Ambulance Service, an air ambulance, Humberside Police and Humberside Fire and Rescue.
A statement from Humberside Fire said: "We're currently attending an incident in Withernsea.
"There are emergency service vehicles around the Central Promenade area. Please avoid this area if possible and take extra care as emergency vehicles are moving in the area."
Temperatures in the seaside town are forecast to drop to freezing overnight.
Earlier, East Riding of Yorkshire council confirmed a severe weather protocol was in place due to the cold.
Hornsea Inshore Rescue, a local independent group of volunteers, earlier said the treacherous conditions had stopped it from launching.
"Called out, unable to launch the lifeboat due to horrendous conditions and 3 metre waves breaking on our slipway which would knock the tractor and trailer sideways off the ramp," it said in a statement on social media this afternoon.
In a post yesterday, the group said it had called off a New Year's Day public swim because "the sea conditions were just not suitable today for us to condone anyone entering the water".
Yesterday in Brighton a 51-year-old man died after getting into difficulty in the water.
So many are like Lupo Guagliumi, still waiting to discover if friends survived. Praying for those he knows are fighting for their lives.
The Italian teenager was in Le Constellation on New Year's Eve, fortunately leaving just before the fire because some friends wanted to go to another party.
He returned to find a scene of horror.
"We were heading back, and we heard what happened, so we rushed over," Guagliumi told Sky News.
"We saw terrible things… we saw flames. Unfortunately, bodies on the floor, people screaming and then police came."
He wanted to help but was ordered back.
"It was traumatising because I had some friends in there and some of them were not answering the phone," he said.
Lost friends
Three friends, he believes, are in intensive care, badly burned after being placed in an induced coma. At least five others are in hospital with lesser burns that are still severe.
"Some are lost, and we don't know where they are. I tried texting them, calling them, they're not answering. So maybe around 10-15 people," he said.
"Not knowing where they are, if they maybe passed, or if they're in a hospital somewhere, not being able to be recognised or IDed."
'The worst thing that could've happened'
It is an agonising position to be in as a 15-year-old who has been coming on holiday from Milan to this resort in the Swiss Alps over the last decade with his family, often three times a year.
Drinking is allowed from the age of 16 in Switzerland, and Le Constellation is believed to have been packed with teenagers to bring in 2026.
Guagliumi had also been there the previous night and shared a photo he took of sparklers in the basement bar.
There was no fear at the time about the dangers they posed; now being blamed for igniting the inferno after being raised in champagne bottles too close to the ceiling.
"It was the worst thing that could have happened on New Year's," he said. "It's hard to know Crans-Montana is now associated with this."
More on this story:
Missing teenagers named
Why ski resort fire spread so quickly
His voice trails, becoming emotional about the resort that brought so much joy now being scarred by trauma, tragedy, and the torment of still not knowing the fate of loved ones.
"I could have stayed there," he said. "It's very scary, seeing as though it could have happened to me as well."
He is alleged to have been driving recklessly and without a valid national licence.
Joshua, a two-time world champion boxer, was travelling in the back of a black SUV when it struck a stationary truck on a major road near Lagos on Monday, killing his friends Latif Ayodele and Sina Ghami.
Ghami was Joshua's strength and conditioning coach, while Ayodele was a trainer and described as being like a "twin brother" to Joshua.
Hours before the accident, Joshua and Ayodele posted clips on social media showing them playing table tennis together.
The Ogun State Police Command on Friday confirmed that the driver of the Lexus SUV, Adeniyi Mobolaji Kayode, had been charged on four counts.
Kayode was charged with dangerous driving causing death, reckless and negligent driving, driving without due care and attention and driving without a valid national driver's licence.
The 46-year-old appeared at the Sagamu Magistrate Court, and the case has been adjourned to 20 January for trial.
On Wednesday local authorities confirmed Joshua, who is British-Nigerian, had been discharged from the hospital and was recuperating at his home in Nigeria.
The 36-year-old boxer and his mother had been "at the funeral home in Lagos this afternoon to pay their final respects to his two departed friends", Lagos state commissioner for information, Gbenga Omotoso, said on social media on Wednesday.