Singer almost fell out of the air during performance in San Francisco on Friday

Fans were left panicked as they captured the heart-stopping moment when the 40-year-old singer belted out her hit song Roar while soaring through the sky on a mechanical butterfly.On Friday, Katy who was dressed in a sparkling crop top and hot pants, initially looked at ease as she glided over the crowds at the Chase Center while singing her track amid her The Lifetimes Tour. However, things took a turn for the worst as she suddenly plunged downwards as the flying stage prop appeared to malfunction.