Police have sealed off an RAF air weapons range amid reports that a soldier has died and another has been injured.
Officers were called to RAF Tain on the Dornoch Firth, in Easter Ross, at 5.55pm on Tuesday to investigate reports of an incident.
A police cordon has been set up around the base as authorities deal with the incident.
Unconfirmed reports suggest that one person has been shot dead and another injured in a live firing training exercise.
The range is used by the RAF and the army and has a rifle range and small arms range as well as bombing ranges.
An Army spokesman said: "We are aware of an incident at the Tain base, near Inverness.
"We will release more information as and when it becomes available. It would be inappropriate for us to comment further at this point."
Police said officers were at the scene.
A Police Scotland spokesman said: "Police are currently in attendance at RAF Tain following reports of an incident.
"A call was received by police at 5.55pm and officers are at the scene."
The Tain range is used by tri-service, US Air Force and other Nato air forces for bombing and strafing practice.
It has 18 separate targets suitable for a variety of weapons and different delivery methods.
Typhoons and Tornados from RAF Lossiemouth are the main air users of the range.
Tain is also responsible for Cape Wrath Range near the village of Durness.
Both ranges employ a number of civilian contracted workers who manage the estate, assist in the control tower, target score and deal with ordnance clearance from the range.
The incident comes a little more than two months after a soldier was shot dead during a live-firing exercise at the Otterburn Training Area in Northumberland.
Private Conor McPherson, 24, a member of The Black Watch, 3rd Battalion, the Royal Regiment of Scotland, sustained a serious head wound on August 22.
And just over a month before Private McPherson's death a soldier died on a training exercise on what was the hottest day of the year in Brecon, south Wales.
Joshua Hoole, from Ecclefechan near Lockerbie, Dumfries and Galloway, was on pre-course training for the Platoon Sergeants' Battle Course when he died on July 19.
The 26-year-old member of The Rifles regiment collapsed after taking part in a fitness test near the Dering Lines infantry training centre at about 6.30am.
Police are investigating the circumstances surrounding both earlier deaths.