A number of people are believed to have been hurt in an incident involving a tank at a military training base in West Wales.
The Ministry of Defence said it was investigating an incident at Castlemartin firing range in which people were understood to have been injured.
Live firing was due to take place at the range in Pembrokeshire from Monday to Friday, according to notice on the government website.
Police and the Welsh Ambulance Service were called to the Royal Armoured Corps range at 3.30pm on Wednesday.
An MoD spokeswoman 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 Dyfed-Powys Police spokeswoman said: “Dyfed-Powys Police were called to an incident at MoD Royal Armoured Corps range in Castlemartin range at 3.30pm today.
“This is being investigated and a further update will be provided when appropriate.”
The ambulance service said it was alerted to the incident just before 3.30pm, and an air ambulance was seen leaving the area.
Castlemartin is the only UK Army range normally available for direct-fire live gunnery exercises and is used by Army, Army reserves and cadets.
It is also used by civilian organisations and research establishments.
The range, opened by the War Office in 1938, covers 5,900 acres on the south Pembrokeshire coast.
A 21-year-old soldier died there in 2012 after being shot in the head while relaxing at a safe location just outside the training range.
An inquest into the death of Ranger 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.