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

Bird flu ripped through a Washington state wildlife sanctuary, killing 20 big cats, the center said in a Facebook post, calling the deaths a "significant loss."

The Wild Felid Advocacy Center in Shelton was home to 37 big cats - including tigers, cougars and leopards - before the outbreak began in late November, said Mark Mathews, who co-founded the sanctuary in 2004. Twenty died from the disease - an even mix of elderly cats with previous medical issues and younger, healthier cats.