Two walkers have been killed and two are in hospital following a series of separate lightning strikes on Corn Du and Cribyn in the Brecon Beacons at the weekend.
Rescue teams were called to the Pen y Fan area at around mid day on Sunday. While dealing with one summit incident they were notified about more casualties on a different top, a situation one longstanding team member described as 'exceptionally unusual'.
Huw Jones, spokesman for Central Beacons Mountain Rescue, told the BBC:
'Our prime concern was to get equipment and personnel up on the tops. So I left with the first party from here - taking medical equipment, a defibrillator just in case.'
'And just as we were getting up onto the summit, a call came through that there was another casualty on one of the other summits.'
'Through the morning, the clouds built up. And off the back of the hot and humid weather that we've had over the last few days, the weather front moving through triggered off the thunder and the lightning.'
'And of course, in a mountainous environment, if there's lightning around, the lightning is going to aim for the highest points.'
The recent warm weather has seen a lot of lightning.
Advice on how to reduce your chances of getting struck.