A swimmer said he feared for his life after he was attacked by otters in a lake at a beauty spot in northern California that left him with around 40 puncture wounds.

Matt Leffers said he was bitten at least 12 times while swimming at Serene Lakes in Placer County, about 90 miles northeast of Sacramento, on September 3.

Leffers told NBC News affiliate KCRA 3 in an interview on Thursday, two months after the attack, that he had been swimming in the lake, where his family has a cabin, for 30 years. But he had never experienced anything like this.

He felt something bite his calf and then suffered another bite within seconds.

“And then I started swimming fast but there was the otter, popped up right in front of me and then I was bit again,” he said.

“These things were so aggressive that, literally, I felt like they wanted to kill me,” he continued. “It is by far the most terrifying experience I’ve ever had in my life. Nothing even comes close.”

Leffers’ wife had to rescue him on a paddleboat and before taking him to the hospital. Pictures shared with KRCA from the hospital show Leffers’ leg badly cut and covered in blood and months later the scars remain.

KCRA 3 spoke to the California Department of Fish and Wildlife, which confirmed that an otter attack took place at Serene Lakes in July — prompting Leffers to call for greater action.

“I think the fact that I’m the second person attacked here this summer, it’s a big red flag,” he said.

Peter Tira, a spokesperson for the California Department of Fish and Wildlife, told KCRA 3 that otters had also attacked dogs in the Redding area. He stressed that while otter attacks on people are very rare, they are a predator species that is very good at swimming and has very sharp teeth.

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“They won’t normally attack people or larger animals. However, they will defend their territory if they feel threatened, whether that’s a real threat or perceived threat,” Tira said.

One theory is that the otters are attracted to the lake and emboldened by its high fish population.

A letter dated September 21 obtained by KCRA 3 from the California Department of Fish and Wildlife to the Serene Lakes community, said that biologists who visited the lake “agreed that the abundance of fish in the lake is a likely cause for otter presence and behavior.”

Leffers said the department’s response was “wimpy.”

“They need to mitigate the situation before somebody gets killed,” he added.

The letter said state wildlife officials were working to confirm the number of otters at Serene Lakes and would develop a strategy once they have more information.

Otter attacks are not unheard of in America. In September a rabid otter bit a man and a dog in Florida before it was captured.

Three women were injured in August when an otter attacked them as they floated on a Montana river.

In July the department reported that a five-year-old sea otter was “aggressively approaching people and biting surfboards,” near Santa Cruz. The department said it planned to capture the creature and place it in a zoo or aquarium.

NBC News has contacted the California Department of Fish and Wildlife for comment.