Sharks were sighted near Monterey Bay
Great white sharks were spotted several times and in different spots in Monterey Bay over the weekend.
At Manresa State Beach, a great white was seen attacking a harbor seal.
California State Parks officials said there's not threat to humans at this time, but they are keeping an eye out for sharks just in case.
Experts said surfers stand a much greater chance of getting struck by lightning, dying in a plane crash or winning the lottery than being killed by a shark.
Despite the weekend great white sightings off the Santa Cruz County coast, people have not stopped surfing or wading in shallow waters.
Debbie Kosier, of Turlock, said she was on the beach on Sunday when she saw something happening about 150 yards from shore.
"The first thing I thought, 'Oh, there's a red boogie board out there.' All we saw was this thrashing and then we saw a bunch of red blood and I said, 'Oh, my god, that's a shark,'" Kosier said.
"It's a good example of the shark being somewhat selective. In other words, if there's a lot of food around it, they won't bother people," said Sean Van Sommeran of Pelagic Shark Research Foundation.
Even so, state park rangers kept a wary eye on ocean water looking for anything unusual.
Experts said they believe great whites are returning from the open ocean to feed on smaller sharks and harbor seals, and they remind people to never swim alone and stay away from the mouths of rivers, where fish and other sea life congregate.