The Marine Mammal Center revealed on Wednesday that four dead gray whales were discovered in the San Francisco Bay Area waters in the last week.

Dead Gray Whales

Witnesses reported the first incident of a dead gray whale last week on Crissy Field. On Saturday, a second one was spotted at Fitzgerald Marine Reserve in Moss Beach.

The third deceased animal was found in San Francisco Bay. While the fourth was discovered washed up on Muir Beach, said the center.

“Both whales found in the Bay were towed to a safe and secure location at Angel Island State Park,” the center said. Experts are conducting an investigation to determine the cause of the animals’ deaths. They are scheduled to perform a necropsy on the most recent dead animal on Thursday.

The center is urging the public to report any sightings of sick or dead marine animals by calling their 24-hour rescue hotline, KRON4 reported.