The commanding officer of a soldier who died on a training exercise in Brecon said his regiment has been left "utterly devastated."
Cpl Joshua Hoole, 26, of Ecclefechan, near Lockerbie, died on pre-course training for the Platoon Sergeants' Battle Course on Tuesday.
He was a member of the Rifles regiment at ITC Catterick.
A post mortem examination is being carried out on Friday and police are continuing their investigations.
The Ministry of Defence confirmed a second soldier was admitted to hospital on the same day and has since been discharged.
A spokeswoman said he was not on the same exercise as Cpl Hoole.
"We seek to make all training as safe as reasonably possible while ensuring that soldiers are ready for the challenges of protecting the United Kingdom. Where practicable all recommendations made in recent inquests have been implemented," she said.
Maj Dean Murch, officer commanding The Rifles, 1st infantry training battalion, said they are "utterly devastated" following the death.
"His family have lost a son, a brother, a fiance and a very special friend," he said.
"Their grief will be inconsolable."
He added: "Truly the thoughts and prayers of every single Rifleman in the Regiment and all his colleagues at the Infantry Training Centre are with them in their hour of need, now and in the forthcoming days and beyond."
Cpl Hoole had just finished an eight-mile course when he collapsed at Dering Lines infantry training centre just before 09:00 BST on Tuesday.
It was the hottest day of the year where temperatures in the Brecon area peaked at just above 30C (86F).
Cpl Hoole's death follows those of three soldiers who were taking part in an SAS training exercise in the Brecon Beacons on one of the hottest days of 2013.
The Ministry of Defence will carry out a full investigation into the death, Defence Minister Harriett Baldwin has confirmed.