John Regan, an accomplished bassist who played with Peter Frampton, David Bowie and Mick Jagger, died on Friday. He was 71.

His cause of death is currently unknown.

Frampton, along with a handful of musicians Regan performed with, mourned his loss on social media.

"There might only be a handful, if that, of people who come into your world and truly enrich your life. I have lost one of my closest buddies," Frampton wrote on Twitter. "He certainly enriched my life because of the person and the great player he was. John Regan was the best of us."

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"He went out of his way to help people when things weren’t right," Frampton continued. "It didn’t matter who you were, prince or pauper. I know there are many of you out there who knew him. He was a friend to all. Always musically inspiring and one of the funniest people on the planet."

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"My thoughts are with his wife Cathy, his children, Christopher and Jeness and his grandchildren," said Frampton. "I love you my brother you will be missed by so many. rest in peace."