A swarm of bees attacked a group of climbers in Brazil last week as they tried to rappel down a 130m waterfall in the Rio Grande do Sol forest.

Two climbers died in the attack after they tried to descend too quickly, lost control and fell to their death. Three other climbers suffered serious injuries including fractured bones and numerous bee stings.

“Bee sting fatalities are not as uncommon as you might think…”

“The bees appeared suddenly, in a huge swarm that came from the woods, and made us go down the cliff. They were already preparing to go down when we were attacked and everything went wrong,” Gomercindo Daniel Filho, one of the surviving climbers, told Brazilian newspaper Folha de S. Paulo.

Two of the surviving climbers hiked 7 miles to the town of Maquiné to get help. Emergency helicopters didn’t arrive at the scene until the next day because the area was hidden deep inside the forest.

Roberto Schuster, the group leader, organises trips for climbing enthusiasts and has been canyoning for over ten years.

Five years ago, the group had an accident at the same waterfall, where a technical failure delayed a rappel and two members spent spent two days lost in the forest, according to Folha de S. Paulo.

Killer bee fatalities are not as uncommon as you might think. Back in 2013, a climber and his dog were killed in Arizona after being attacked by a swarm of Africanised honey bees while bolting a cliff in the Santa Rita mountains.