Police dispatch traffic indicated that a "74-year-old male was pulled out of the water, advising he was bit by a shark," but police and wildlife authorities have not confirmed that the swimmer was bitten by a shark. Officials have said only that the man was bitten by a small marine animal early Monday afternoon.
"Everything is just pure speculation at this point. The subject did have some bite marks on his lower leg. They look like small puncture wounds," Foster City Police Lt. David Orlando said.
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Residents familiar with the lagoon offered theories about what may have caused the bite.
"The only sharks I know in here are probably leopard sharks; they come in from the Bay as babies and then they grow larger," said Nathan Ng, a Foster City resident.
"We did hear stories when we were very young that a shark, a little shark, might be able to get through the filter system once in a while. Personally, I've never seen it and have never heard of anybody being bitten by anything," said Traci Butler, who grew up in Foster City.
Otters have also been spotted along the water's edge in Foster City.
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A witness told ABC7 Eyewitness News that the swimmer was yelling for help. According to the witness, her husband reached into the water, grabbed the man and pulled him to safety.
They did not see the animal involved, but said she saw blood coming from the swimmer's leg.
"I've been here over 23 years, I've never heard of it happening here in the lagoon. This is the first time I've heard of any kind of interaction between a person and any marine wildlife of any kind," Orlando said.
"Just shocking because so far we have never heard this," said Shobha Ketker, who was with friends in a park along the lagoon Monday.
The investigation remains ongoing, and police are advising people to watch for any unusual marine animal activity in the lagoon.