An inquiry into the deaths of two soldiers and the serious injury of two others at a Ministry of Defence base in Pembrokeshire is continuing.
The Royal Tank Regiment soldiers died after the incident at Castlemartin Range on Wednesday.
The MoD, Dyfed-Powys Police and Health and Safety Executive are investigating.
The incident is understood to have involved ammunition. The MoD has suspended tank live firing exercises by British military as a precaution.
The second death was announced on Thursday night by Minister for Defence, People and Veterans, Tobias Ellwood.
It followed an earlier announcement of the first soldier’s death on Thursday morning.
A wreath has been laid at the Tank Memorial Ypres Salient in Belgium – which honours tank soldiers killed in the world wars – in tribute to those who died at Castlemartin.
Flags at the camp have been lowered to half mast.
The MoD suspended tank live firing exercises as a precaution following the incident until the outcome of the investigation is known.
This applies to all British military, wherever they are in the world.
No personal details of those involved have been given.
Lt Col John Skipper, defence analyst and former military intelligence officer, told the BBC’s Good Morning Wales programme the safety record at Castlemartin was “excellent”.
He said: “There are very, very few incidents given the very high level of training there, millions of rounds are fired there in the 44 weeks they’re open every year.”
He said Challenger 2 tanks were used at the range, one of two armoured fighting vehicle training areas in the UK where direct live firing exercises and vehicles manoeuvres take place.
The 1st and 2nd Royal Tank Regiments merged in August 2014 to form The Royal Tank Regiment, which is based in Tidworth, Wiltshire.
The Army’s website said the regiment was “preparing for a live fire exercise at Castlemartin in Wales”, which was scheduled to take place at the range between Monday and Friday.