Kim Shattuck, lead singer of punk rock band The Muffs, died at 56 after complications with ALS, her rep confirmed.

“I'm sorry to confirm she has passed away,” Joel Miller told USA TODAY in a statement. ALS, also known as Lou Gehrig's disease, is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord, according to the ALS Association.

In the early '90s, The Muffs were known for songs such as “Sad Tomorrow” and “Lonely Boy” and recorded a cover of Kim Wilde's 1981 hit “Kids in America” for the movie “Clueless.”

The Muffs released their self-titled debut album in 1993 and went on to release five other albums over two decades. The Muffs' latest album, “No Holiday,” is set to be released this month.

Before joining The Muffs, Shattuck was lead singer for The Pandoras from 1985 to 1990.

She had a short stint as the bassist for the Pixies, which she told Rolling Stone ended with her dismissal.