She wrote: 'i cant even breath right now im crying so hard i just lost 1 of my best friends. i love you forever Amy & will never forget the real you!'
The shock and sadness was evident from all who wrote on the micro-blogging site.
Kelly with Amy at the ELLE Style Awards four years ago at The Roundhouse in North London where the singer made her last public appearance on Wednesday
Radio DJ FEARNE COTTON: 'Can not believe the news. Amy was a special girl. The saddest news.'