Hall and Oates Bassist, Tom T-Bone Wolk, is dead from what appears to be a heart attack.

Wolk, 58, collapsed Saturday night in Pawling, N.Y. hours after a studio session with Daryl Hall; they had been recording a solo album together. Hall and Oates were set to appear as part of the one-year anniversary show for NBC’s ‘Late Night with Jimmy Fallon’ on Monday night.

Wolk not only performed with Hall and Oates for 30 years, he also worked with a variety of artists such as Elvis Costello, Bette Midler, Billy Joel, Carly Simon, Rosanne Cash, and Avril Lavigne. He played bass in the ‘Saturday Night Live’ house band from 1986 to 1992.

Daryl Hall of Hall and Oates said of Wolk, “It’s not if I will go on, but how.” He continued, “T-Bone was one of the most sensitive and good human beings that I have ever known.”

Wolk began playing with Daryl Hall and John Oates during the recording of their very popular ‘Private Eyes’ album in 1981. In recent years Wolk was named music director for Hall and Oates.

Wolk joked that he was “that guy with the hat” at Hall & Oates concerts.

Funeral details have yet to be announced.