A bird flu outbreak around Fort Flagler State Park near Port Townsend may be spreading to mammals, according to the state Department of Health.

As of last week, an outbreak of a deadly strain of the avian influenza had likely killed 1,700 gulls and Caspian terns on Rat Island – a small wildlife preserve near the state park, and its adjacent shores. The island is currently closed due to the outbreak.

The Department of Health said Friday that preliminary results show three harbor seals in the area have likely been infected with the disease, though confirmation testing is still pending.