REO Speedwagon guitarist Gary Richrath passed away on Sunday, according to a post on the band’s Facebook page from singer Kevin Cronin. He was 65. A cause of death has not yet been revealed.

Richrath joined REO Speedwagon in 1970 shortly before the band released their debut, self-titled effort. Throughout his nearly 30-year tenure with the group, the guitarist wrote several of the band’s biggest tunes including “Take It on the Run” and “In Your Letter.”

Read the full message from Kevin Cronin below.

Hi friends, kc here. My longtime friend and collaborator Gary Richrath passed away earlier today. I feel so sad. Gary was both a unique guitarist and songwriter, and the embodiment of the tough guy with a heart of gold. I learned most of what I know about being in a rock band from Gary Richrath. The entire REO Family mourns his death and shares in the grief of his family, friends, and fans. These words do not come close to expressing the depth of emotions I am feeling at this time…kc