Jack Sonni, former guitarist for British rock band Dire Straits, has died, the group announced on social media.

"#JackSonni Rest In Peace" the band wrote on X, formerly known as Twitter, on Thursday alongside a black and white photograph of the guitarist. He was 68.

Sonni, who was born in Indiana, Pennsylvania, met founding Dire Straits members and guitarists David and Mark Knopfler while working in a guitar shop in Manhattan in 1978, according to a post on the Dire Straits Blog, which was shared by the band on social media.

The Knopflers had founded the band the year before with bassist John Illsley and drummer Pick Withers.

Affectionately known as "the other guitarist" -- a label he embraced in the biography on his own website -- Sonni began to play with the band, including for the album "Brothers in Arms," which shot to international success, and the subsequent tour.

The album spent 14 weeks at number one in the UK following its release in 1985, and nine weeks at number one in the Billboard Top 200. The album went on to sell more than 30 million copies worldwide, according to the band's official website. "Brothers in Arms" is credited with being the first album to sell more than one million copies in CD format, according to Billboard.

"So sorry to hear the sad news that Jack Sonni has died, we loved having him with us on the Brothers in Arms tour, fond memories," Illsley wrote in a post on Facebook Thursday.

Alongside his musical career, Sonni was also a writer and hosted a podcast, "The Leisure Class with Jack Sonni."