Bird flu has been on the rise in Washington state and one sanctuary was hit hard: 20 big cats – more than half of the facility’s population – died over the course of weeks.

The Wild Felid Advocacy Center of Washington announced it is under quarantine amid a devastating bird flu outbreak that has killed 20 big cats.

Nearly two dozen big cats died after bird flu swept through the sanctuary where they lived. The Wild Felid Advocacy Center near Shelton, Washington said the first animals died last month but the cause was just recently confirmed, KIRO reported. In all 20 cats died, more than half of the sanctuary’s big cats.