One soldier has died and another has been injured at an Army training area, the Ministry of Defence (MoD) said.
The incident, which is thought to have involved a vehicle rolling over, happened at the Army's Warcop training area.
Warcop, near Appleby in Cumbria, is used as an MoD live firing area.
An MoD spokeswoman said: "We can confirm that there has been one fatality in an incident at Warcop training this morning. Next of kin have been informed.
"Another person was injured. An investigation is under way to establish what happened."
Great North Air Ambulance said it flew a teenager to hospital in Middlesbrough after the incident.
It tweeted: "We were called to Warcop at 11.05am after a vehicle overturned. A 19-year-old male was flown to Mboro with chest and back injuries. He was stable."