Donna Summers died today at 63 years old after battling cancer (TMZ). Rock stars are already weighing in on her death and her importance to music.

Alex Skolnick (Testament) tweeted that her music “always had great feel, more so than typical ‘disco’ artists.” He also referenced the track “Burning Up With Fever” from Gene Simmons’ solo album, which featured Summers.

Tom Morello (Rage Against The Machine) honored Summers’ music on Twitter too. “Thanks for the all time great disco jams,” tweeted the inventive guitarist.