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.

A wildlife sanctuary in Washington state is under quarantine after 20 big cats died due to H5N1 bird flu infections.

The sanctuary in Washington state said it was working with officials to determine the cause of the outbreak, which has killed over half of its cats in recent weeks.