One member of air crew has died and two others remain unaccounted for after two Tornado jets crashed off the coast of Scotland yesterday, the Ministry of Defence (MoD) said.
The man who died was an officer from 15 (Reserve) Squadron, based at RAF Lossiemouth in Moray.
A fourth crew member is in a serious but stable condition in hospital.
There is "no expectation" of recovering the missing people alive, Group Captain Ian Gale, the station commander at the RAF base, said.
The name of the officer who died has not yet been released.
Mr Gale said today's decision not to resume the search and rescue operation for the missing crew was due to "extremely poor" weather conditions in the area.
The recovery operation will resume as soon as possible.
Mr Gale said the incident will be subject to a full investigation.
He said in a statement: "Following the incident involving two of our Tornado GR4 aircraft in the Moray Firth yesterday, it is with great sadness that I must confirm the death of one of the crew members, an officer from 15 (Reserve) Squadron, based here at RAF Lossiemouth.
"A second crew member remains under medical care, where he is in a serious but stable condition.
"Two additional personnel remain unaccounted for. Due to extremely poor weather conditions in the area, the RAF and Her Majesty's Coastguard have made a joint decision not to resume search and rescue operations.
"The operation will be resumed as a recovery operation as soon as possible, but we must be realistic: given the length of time that has elapsed since the accident, there is no expectation of recovering missing personnel alive.
"The Royal Air Force is in contact with the next of kin of all those involved. As I am sure you will understand, they have asked for a period of time to take in the news and inform extended family members before further details are released. The Royal Air Force intend to respect this and I would ask the media to do likewise.
"Clearly, this incident will be subject to full investigation, and a service inquiry will be led by the Military Aviation Authority. It is important that we establish the facts of what happened and it is vital that the investigation is allowed to take its course. But the priority now is to ensure that the families of those involved receive the support they need at this most difficult of times."
The RAF ensign at the entrance to the Lossiemouth base was lowered to half-mast this afternoon.
There have been no flights in and out of the base today.
Prime Minister David Cameron paid tribute to the personnel involved in the crash.
He said: "Our thoughts should be with the friends, family and colleagues of those involved.
"The circumstances still remain uncertain but it's clearly a very serious incident.
"The investigation is ongoing and more details will be released by the RAF in due course."
The Tornado GR4s came down in the Moray Firth yesterday afternoon.
Aberdeen Coastguard contacted the RNLI for assistance at about 1.50pm after reports that the jets had come down 25 miles (40km) south of Wick.
About 15 lifeboat volunteers joined the rescue operation in boats from Wick, Invergordon and Buckie.
The boats headed for the Beatrice oil field area supported by a helicopter from Stornoway in the Western Isles.
Wreckage seen being brought ashore by Buckie lifeboats last night included a liquid oxygen canister and a flying glove.
Crew from the Buckie boat reported that two people were taken from the sea by helicopter and flown to Raigmore Hospital in Inverness.
The search for the remaining people was stood down last night as bad weather hampered the rescue effort.
The Maritime and Coastguard Agency later said the search-and-rescue element of the response has been "terminated" and the mission moved into a recovery phase.
A spokesman said they were continuing to offer assistance to the Ministry of Defence.
Richard Lochhead, the MSP for Moray, said the whole community was in shock and the crash was a tragedy.
He said: "Given that thousands of people in the area work at the base, everyone has a connection with it and everyone will be thinking about the families of crews who have been involved in this incident and their friends and colleagues that work at RAF Lossiemouth.
"Clearly, when an incident like this happens, people are very shocked and begin to ask questions.
"But the pilots are training in very extreme circumstances, it's a very high-risk job flying fast jets and training for conflict.
"This is a very serious incident and people will ask questions, that's only natural, but now's not the time to speculate on the cause of this incident. There will be an investigation, of course, and we will have to wait for that.
"People who have questions should ask them and they should be answered.
"When a tragedy like this happens on such a huge scale it still causes a huge shock and people are now thinking of the crews and their friends and families at this difficult time."
In January last year, two RAF crew were rescued after their Tornado GR4 jet came down in the sea off the west coast of Scotland.
The crew, from RAF Lossiemouth, ejected from the plane before it landed in the water at Loch Ewe near Gairloch, Wester Ross.
RAF Lossiemouth, on the Moray Firth coast, is home to three squadrons of Tornado GR4s.
The Tornado GR4 is a two-seat attack aircraft capable of delivering a variety of weapons and reaching a maximum altitude of 50,000ft (15,240m).
In July 2009, an RAF pilot and navigator were killed when their Tornado jet crash into a hillside in Argyll.
Flight Lieutenant Kenneth Thompson, 27, and Flight Lieutenant Nigel Morton, 43, died in the crash near the village of Arrochar.
The aircraft was an RAF Leuchars-based Tornado F3 on a routine flight.
First Minister Alex Salmond said: "This is tragic news and my sincere sympathy is with those loved ones who have been bereaved, and indeed all those affected.
"RAF Lossiemouth is at the heart of the community in Moray and I know how deeply and painfully this will touch not just the personnel and families directly connected with the base, but the whole region.
"The rescue services have worked incredibly hard in the hope of a different outcome and the Scottish Government remains ready to help in any way we can with the next phase of this operation."
Shadow Scottish Secretary Margaret Curran said: "This is an extremely distressing development and my heart goes out to the families and friends of those involved.
"Those heroes who serve their country take extraordinary risks, both in training and in combat, and all our thoughts are with them at this difficult and tragic time."
Scottish Conservative Highlands and Islands MSP Mary Scanlon said: "This is a tragic incident even with all the risks known to these airmen.
"Our thoughts are with the families at this time of unexpected tragedy.
"Moray felt the loss of the Nimrod crew over Afghanistan in 2006 - an event that stunned the community.
"This event closer to the airbase is a heartfelt tragedy for all the families.
"I trust that a full and thorough investigation will take place in order to establish the cause of the accident."