Two cases of bird flu have been detected at the Metro Richmond Zoo in Virginia, marking the first time the highly contagious virus has been found at the facility in its 30-year history. The cases come on the heels of at least three other recent outbreaks in the Washington region that have already killed an estimated 1 million chickens and put officials on alert.

The widening U.S. bird flu outbreak has made its way to Maryland, which has counted two cases on commercial poultry farms — one in Caroline County and another in Queen Anne’s County — since the start of the year.

A broiler farm in Dorchester County, Maryland, has received a preliminary positive test for highly pathogenic avian influenza.