Officers in a California Highway Patrol helicopter spotted what appeared to be a great white shark swimming near a Bay Area pier on Friday afternoon.
According to the CHP, the helicopter was on patrol just before 12:30 p.m. when they saw the shark swimming in the Pacific Ocean, about 100 yards off the Pacifica Pier.
The CHP notified the Pacifica Police Department, which posted shark warning signs near the beach, ABC 7 reported.
NBC reported that the shark was 12 feet long and didn't show any aggressive behavior.
Stanford University marine biologist Barbara Block, who recently led an expedition to the White Shark Cafe in the Pacific Ocean, told ABC 7 that the shark could possibly be a "sub-adult," younger shark "hunting for a marine mammal."
ABC 7 reported that great whites aren't usually spotted in the Bay Area at this time of year. They're more commonly seen in September or October, when the Pacific gets warmer.
"While shark sightings are not frequently reported, the Pacific coast is part of the natural habitat for sharks," police said in a statement to the Mercury News, adding that they urge beachgoers to be cautious and aware of their surroundings.
Experts say they've noticed an increase in the number of great white sharks in the last 10 to 15 years, possibly due to environmental protections, according to the San Diego Union-Tribune.
In 2013, the California Fish and Game Commission voted to designate the great white shark as a candidate for protection under the state's endangered species act, Reuters reported.
A year later, based on the recommendation of the California Department of Fish and Wildlife, the commission determined that listing the great white shark as a threatened or endangered species wasn't necessary.
However, the shark's been off-limits to commercial and sport fishing in California since 1994, and it's also illegal to pursue, capture or kill them, including by intentionally attracting them with "bait or other methods," according to Fish and Wildlife.