At least three hikers fell ill on countryside trails as temperatures in parts of Hong Kong climbed to a sweltering 33 degrees Celsius (91 Fahrenheit) on Sunday. A 25-year-old visitor was suspected of suffering from heatstroke while he hiked with friends on the popular High Island Reservoir East Dam-Po Pin Chau hiking route in Sai Kung at about noon. A government helicopter airlifted him to Ruttonjee Hospital in Wan Chai for treatment.