A 24-year-old man has collapsed and died while hiking in Sai Kung. Another person, aged 50, also collapsed.
They were both airlifted to Eastern Hospital by helicopter, where the 24-year-old was declared dead.
The 50-year-old is now conscious.
They were part of a group of about 20 hikers.
The very hot weather warning had been issued earlier in the day, with the government warning people against outdoor activity.