A hiker is fighting for his life after being stung more than 100 times by bees on a mountain in Arizona.
He rang emergency services in Phoenix because his injuries meant he couldn't continue his descent from Lookout Mountain.
Rescue teams dispatched a helicopter and winched him to safety, before transferring him to an ambulance to take him to hospital.
Officials say he is fighting for his life.
Phoenix Fire Department has urged hikers to avoid disturbing hives, wear light-coloured clothing, and not to use scented products while outdoors.
Anyone who encounters a swarm is advised to run away quickly while protecting their head and face - taking extra care to cover their mouth.
Dr Frank Lovecchio, a professor at Arizona State University, has said the venom from repeated bee stings effectively "crushes your muscle".
He told FOX 10 that bees in Arizona are highly aggressive - and it is not uncommon for someone to be stung hundreds of times in a single incident.
"It's always about protecting the queen bee, protecting the hive," he said.
"And it sends signals that the other bees come over and kind of attack you."
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An unusually warm winter has caused bee activity to rise in Arizona, and this is the latest in a long line of incidents.
Last week, five people were stung, with one taken to hospital, after a swarm disrupted a women's lacrosse game at a university campus in Tempe.
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