(NBC News) — A swimmer said he feared for his life after he was attacked by otters in a scenic Northern California lake, leaving 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 Sept. 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.

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