BIG LAKE, Minn. (WCCO) – An electric jolt knocked a man unconscious Thursday after witnesses say he dropped a charging boat battery in Eagle Lake while standing in the water.

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Dan Petersen dropped the battery around 2:30 p.m. as friends and family gathered to celebrate the Fourth of July.

“Don’t know how or why, but he fell into the water with the battery charger hooked up,” said Matt Meyer, a friend.

Petersen’s sister, Kris, then ran to help.

“Ran in the water to get him, and she got jolted, too,” Meyer said.

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A third person then ran in to grab Kris, but that person wasn’t shocked.

Once Dan and Kris were out of the water, their friends performed CPR. Meyers said Kris eventually came to. Petersen didn’t.

A helicopter airlifted Petersen to North Memorial Medical Center.

“He was breathing when he left, and had a pulse, but that’s all we know,” Meyers said.

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An ambulance brought Kris to a hospital in St. Cloud, witnesses said.