Madsen died from cardiac arrest, his manager Ron Smith told NBC News. Cardiac arrest occurs when the heart stops functioning. It can lead to death without immediate treatment, according to Mayo Clinic.

Actor Michael Madsen got sober before his death last week, though the 67-year-old star’s condition at the time of his death isn’t known.

Michael Madsen's sister, Virginia Madsen, shared a moving post about the actor who died on Thursday from cardiac arrest. He was 67. The actress shared a black and white photo of the siblings on Instagram along with a message on behalf of her and their family.