A Royal Navy spokesperson said: "It is with deep sadness that we can confirm three members of the Royal Navy have died during a helicopter training exercise.
"Our thoughts and sympathies are with their families and friends at this sad time."
The head of the Navy, General Sir Gwyn Jenkins, added in a statement that he was "deeply saddened to share the news," and said the helicopter was a Merlin Mk4.
"I know this will come as a huge shock to all in our Naval community, and my deepest condolences go out to the families, friends and loved ones impacted by this tragedy," he said.
"I would like to thank Devon and Cornwall Police and the search and rescue teams who responded to the incident this morning.
"An investigation is under way, and further updates will be provided in due course."
Devon and Cornwall Police said earlier that emergency services were at the scene of the incident at Sourton Down, near Okehampton.
The Navy added on Wednesday morning that the crash happened just before 4am.
Several road closures were in place around the A386 and A30 Sourton Cross area after the incident.
According to Traffic England, disruption was expected on the A30 eastbound exit slip to the A386 until around 12.30pm.
The Royal Navy's two air bases are located close to Devon: RNAS Culdrose, one of Europe's largest helicopter bases, is located near Helston in Cornwall, while RNAS Yeovilton in Somerset houses more than 100 aircraft.
The scene of the crash is close to Okehampton battle camp, a military facility on the edge of Dartmoor which has been used for training Merlin helicopter crews from the Commando Helicopter Force.
Merlin helicopters, such as the Merlin Mk4 involved in the incident, usually have a crew of four and can carry up to 24 troops.
Sir Keir Starmer called the incident "utterly tragic," and said: "My thoughts are with the families, friends and loved ones of the three members of the Royal Navy who sadly lost their lives this morning.
"Thank you to the emergency services responding to this horrific incident."
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Defence Secretary John Healey said in a statement that the three Navy staff "served with excellence and will be much missed".
"All our thoughts are with their families, friends and those they served with at this incredibly sad time," he added.
The King is aware of the helicopter crash and will write privately to the families of the three dead, it is understood.
The Princess of Wales, who is commodore-in-chief of the Fleet Air Arm, said in a personally signed message that she was "saddened" to hear of the deaths, adding: "William and I hold their families and friends in our hearts at this very difficult time."
It is understood Kate and the Prince of Wales will be in touch with the families of those who died in the coming days.
Johannes Natland, 19, was allegedly directed to a stash of money, guns and ammunition after he was recruited by the Foxtrot network.
Prosecutors say the organisation is a Swedish organised crime group "used by the Iranian regime", which offered up to 25,000 euros to carry out the hit.
Natland, from Stavanger, in south-west Norway, was arrested on 19 March last year in a hotel room in Huddersfield, West Yorkshire, with a semi-automatic pistol, a revolver and 12 rounds of live ammunition.
Jurors were told the teenager has pleaded guilty to possession of the two guns and the bullets, but denies conspiracy to murder between 1 and 20 March last year. Jurors were shown footage of him handling the weapons on the hotel bed.
"On 17 March last year the defendant Johannes Natland travelled from his home country of Norway to this country to murder," said prosecutor Alistair Richardson.
"He had been recruited by an organisation called the Foxtrot network to an agreement that in return for money he would travel here and undertake a hit.
"He was directed by others to a hotel, to a stash of money and then a stash of guns and ammunition.
"He was prevented from committing murder when he was arrested inside a hotel room in Huddersfield with two firearms and live ammunition."
The court heard the Foxtrot network, which was formed in 2021, has been involved in drug smuggling and violent crimes which are advertised in group chats on social media apps such as Snapchat, Telegram and Signal.
Online groups can have thousands of members including "instigators", "recruiters" and "facilitators" who direct often very young "enforcers", who rarely have any advanced knowledge of who the target is.
A jury was told the alleged murder plot was directed by someone with the username "Agent 47" who asked another Norwegian teenager, "Generalen", who was acting as a recruiter: "Do you have an assassin abroad?"
Agent 47 had said the job was in "Great Britain. As easy as can be," and told him there was 25,000 Euros "in the pot".
The court heard, in a Snapchat conversation on 15 March last year, Natland asked Generalen: "Who is to be shot?"
Mr Richardson said from those first messages it was clear Natland knew the agreement he was entering into involved "someone being murdered and murdered with a gun".
He then told his girlfriend, "I'm going on a crazy mission", the court heard.
The jury was told Natland flew into Manchester Airport on 17 March last year, when he was aged just 18 on a temporary passport.
He was questioned by Border Force officers and refused entry to the UK, but released on bail before taking a taxi to a hotel in Manchester.
The following day, Agent 47 directed Natland to an address in Huddersfield to collect money before the teenager booked a room for three days at the Briar Court Hotel.
Natland was then directed to another address and sent a video and map showing the route to the base of a tree, where he allegedly picked up the guns and ammunition.
The court heard he bought three pairs of workman-style black and orange gloves before being sent to a stolen car, which was allegedly for use in the planned murder the following day.
"He neither knew nor cared who he was to kill," said the prosecutor.
"This was to him all about the money which he would receive for completing the job."
The court heard Natland pretended to shoot firearms officers with his hand when they knocked on the door. Along with the guns and ammunition, they found £2,000 in cash.
The trial, which is due to last up to three weeks, continues.
Several have been left injured after the blaze at the building in the Malviya Nagar neighbourhood in the southern part of the city, which had a restaurant on the ground floor and a hotel above.
Eight fire engines were used to extinguish the blaze and more than 40 people were rescued and taken to nearby hospitals, Delhi police said.
The cause of the fire was not immediately known.
Images from the scene showed firefighters battling to control the fire as thick smoke billowed from the building.
Some people trapped inside could be seen hanging from windows and shouting for help as flames and smoke whipped through parts of the building.
Local residents also joined rescue efforts, helping evacuate those trapped inside and carrying some of the injured to safety.
TV footage showed two people jumping from a higher floor of the building as it was engulfed in flames.
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Some of the victims were foreign nationals who had travelled to India for medical treatment, local media reports said.
They included people from Bangladesh, Nigeria, Mozambique and Liberia, broadcaster CNN-News18 said.
Foreign patients travelling to New Delhi for medical treatment often stay in nearby hotels or residential accommodation during their visits.
Prime Minister Narendra Modi expressed his condolences over the deaths, his office said in a post on X.
It also said the families of those killed would receive 200,000 rupees (£1,600) each in financial assistance.
The government explained where the money was coming from, and what it would be spent on, months after it granted the 500-acre site in Bedfordshire permission to begin the first phase of works.
Universal, which is owned by Sky News' US parent company Comcast, wants to open the attraction in 2031. It is to be called Universal United Kingdom Resort and include a 500-room hotel and retail and entertainment complex.
But local infrastructure, including transport, has to be brought up to scratch first.
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As part of the £1.3bn investment, the Department for Transport is to hand over an expected £474m for local road and rail improvements.
A further £838m, some of which is conditional on community works being completed by the developer, is due to be paid in the form of grants including through the Regional Growth Fund.
The company's total investment in the complex will top £5bn during the construction phase and £1bn in capital investment over the first 10 years of operation.
It is estimated the park, just south of Bedford, will generate nearly £50bn for the economy by 2055 with annual visitor numbers put at an estimated eight million plus.
The project is expected to create about 28,000 jobs - nearly 20,000 during the construction phase - and 8,000 more in hospitality and the creative industries when it opens.
Under its commitments, Universal is to work with local colleges and universities to train students for hospitality jobs.
The site is near the A421, a major road connecting Cambridge through Milton Keynes to Oxford. The road will be among those improved ahead of the park opening.
To help the area cope with increased footfall, upgrades will be made to Bedford station, and a new station built at nearby Wixams under the plans.
Speaking during a visit to the theme park site, Chancellor Rachel Reeves said: "This landmark investment in the heart of the Oxford to Cambridge Growth Corridor will unlock nearly £50bn of economic growth and create tens of thousands of jobs across Bedfordshire in construction, hospitality, creative and technology sectors.
"Our own investment in transport and infrastructure means that local people will benefit - improving connectivity, backing our creative industries, and bringing millions of visitors to the UK from across the world."
The expansion of Luton Airport is expected to play a big role in bolstering ease of access.
No details have yet been released about the expected attractions.
Universal is known for franchises that lend themselves to themed rides, including Minions, Fast and the Furious and Jurassic World.
Mark Woodbury, chairman and CEO of Universal Destinations & Experiences, said: "Today marks a significant milestone on our journey to bring Universal United Kingdom Resort, featuring immersive storytelling, thrilling attractions and unparalleled creativity and innovation to the UK.
"This new theme park and resort will create so many new opportunities for the people of Bedford and beyond and allow us to share our distinct experiences with guests from around the world."
Harinder Kaur, 39, assisted by a Punjabi interpreter, was addressed by a judge at Leicester Crown Court on Wednesday.
Kaur, of Sutton Dene in Hounslow, west London, was charged with the offences on Tuesday.
Leicestershire Police said the body of a man in his 30s was found in a Ford Transit van in a car park in Garden Street, Leicester, at about 5.30pm on 27 May when a member of the public reported concerns about the condition of the vehicle.
The van was registered to a west London address.
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Prosecution counsel Elizabeth Dodds told Judge Timothy Spencer KC a request to transfer the case from Leicester Crown Court to the Old Bailey in London, because the crime scene and many witnesses are in the city, had been successful.
The judge told Kaur: "You face a murder charge, the most serious charge."
He later said: "Your case is going to go to the Central Criminal Court, otherwise known as the Old Bailey, and I am told you will be taken there on Friday.
"You can go down now, thank you."
The case, initially investigated by the East Midlands Special Operations Unit with help from Leicestershire Police, was transferred to the Metropolitan Police.
Officers issued a plea on Tuesday for anyone with information, doorbell or dashcam footage that may have captured a white Ford Transit with the registration BF18 VNV travelling to Leicester from London to contact police.