Two RAF crew died today when their Tornado fighter jet crashed near a beauty spot, the Ministry of Defence confirmed.
A major search was launched after the jet ploughed into a hill near Arrochar, Argyll.
An MoD spokesman said: "It is with deep regret that the Ministry of Defence must confirm the deaths of two RAF air crew from 43 Squadron, RAF Leuchars, in a Tornado F3 crash today.
"The aircraft crashed during a routine training flight at 11.45am at Glen Kinglas in Argyll.
"The next of kin have been informed and have requested a period of 24 hours grace before further details are released."
The spokesman for the Ministry of Defence continued: "At the moment our thoughts and prayers are with the families, friends and colleagues of the two aircrew who lost their lives today.
"The crash is being investigated at the moment.
"There will be a service inquiry held by the RAF."
The crash happened at 11.45am close to the Rest And Be Thankful tourist spot near the village of Arrochar on the A83, west of Loch Lomond.
Search and rescue helicopters from the HMS Gannett naval base and RAF Lossiemouth were scrambled to search the remote countryside for the wreckage and the crew.
No civilians are thought to have been hurt in the accident.
Air accident investigators will also be attending in a bid to establish the cause of the crash.
Witnesses said planes appeared to have been flying much lower than usual today.
Weather in the area at the time was said to be overcast with thick cloud.
Andy Graham, 60, a retired rigger who moved to Arrochar three years ago, said he saw two Tornados flying low in the area around lunchtime.
He said: "We get jets flying over here on training exercises quite regularly. It's not unusual to see them and you definitely hear them.
"But today they seemed to be flying much lower than normal.
"We watched them fly along the loch, up through the glen and towards the Rest And Be Thankful."
An RAF spokesman said there had been a small blaze at the scene which the fire service dealt with.
Strathclyde Fire and Rescue said it had sent five fire appliances, two major incident units with heavy rescue equipment and a support unit to deal with hazardous materials and environmental issues.
The F3 came into service with the RAF in the 1980s.
The pilot in the front seat flies the aircraft, while the rear seat weapons systems officer controls the radar and defensive countermeasures systems.
The Rest And Be Thankful is a pass and road junction between Loch Long and Loch Fyne.
It takes its name from the inscription on a rough stone bench at its 860ft summit.
