A 48-hour worldwide ban has been placed on the use of ammunition deployed during a training exercise at a live firing range after an incident left one soldier dead and three injured.
A member of the Royal Tank Regiment died after being injured in Pembrokeshire, yesterday afternoon.
The MoD is investigating events at a military training base in Wales on Wednesday afternoon.
Police were called to the incident at Castlemartin Ranges - an area of land used for tank training exercises by the Royal Armoured Corps.
A firing notice on the Government's website suggested live firing was expected on the range from Monday to Friday and night firing was due to take place on Tuesday and Thursday.
A spokesperson for the MoD said: "We are aware of an incident at Castlemartin ranges.
"This is still being investigated and therefore it would be inappropriate to comment further."
A spokeswoman for Dyfed-Powys Police said:
"Dyfed-Powys Police were called to an incident at MoD Royal Armoured Corps range in Castlemartin range at 3.30pm (Wednesday).
"This is being investigated and a further update will be provided when appropriate."
The Welsh Ambulance service has said that they responded to an incident this afternoon at 3.26pm at Castlemartin.
The Mid and West Wales Fire and Rescue service has also confirmed they were involved.
An air ambulance was seen leaving the area.
A Royal Tank Regiment statement said:
Castlemartin covers almost 6,000 acres on the Pembrokeshire coast and was requisitioned by the War Office in 1938.
It is the only UK army range normally available for armoured units for direct-fire live gunnery exercises and is used by the Army, Army Reserve and cadets, as well as civilian organisations and research establishments.
The incident comes five years after a 21-year-old soldier died at Castlemartin when he was shot in the head while relaxing at a safe location just outside the training range.
A 2013 inquest into the death of Michael "Mike" Maguire heard he was hit in the temple by a single machine gun bullet fired by a fellow soldier during a training exercise.
The inquest jury ruled Ranger Maguire, who was a member of the 1st Battalion, The Royal Irish Regiment, had been unlawfully killed.