SAN FRANCISCO (KGO) -- Humpback whales were spotted swimming in San Francisco Bay on Thursday.
WATCH VIDEO: Experts urge boaters to keep distance from whales in SF Bay
Sky7 HD was over the huge marine mammals as they swam just inside the Golden Gate Bridge.
We saw as many as four whales so far, but there may be more.
WATCH VIDEO: Humpback whales return, swim off coast of Lands End near SF
Marine biologists believe the humpbacks are being attracted by large numbers of anchovies swimming along the bay's shoreline.
Click here for more stories about whales!
Humpback whales swim near Golden Gate Bridge