Well this certainly came out of nowhere!

Though the sky over Lake Cuyamaca near San Diego, Calif., was beginning to darken on Tuesday when Hans Nansen was filming an approaching storm, there were few warning signs that a bolt of lightning would suddenly shoot from the sky and hit him in the foot, knocking him to the ground.

But suddenly, a bolt struck the ground about 10 feet in front of him, and he saw a streamer bolt connect with his foot. "I saw it go into my shoe," Nansen told The Huffington Post over the phone Monday morning. "My whole leg was sore for a good five days after."

He also said, "A meteorologist from the National Weather Service told me I'd be dead if that main bolt had hit me."

Click the video above to watch.

Nansen said the storm was still a long way off when the bolt knocked him off his feet. "There was no rain. There were blue skies above us," he said.

But lightning specialist John Jensenius of the National Oceanic and Atmospheric Administration, or NOAA, told HuffPost in an email Monday that lightning can strike 10 miles from the edge of a storm, which is about the distance that you can hear thunder from a storm.

"If you can hear thunder (even a distant rumble), you are likely within striking distance of a storm and need to get to a safe place immediately," Jensenius said. "This storm [in the video] appears to be much, much closer than 10 miles."

There have been 21 lightning fatalities in the U.S. this year. They are documented on the NOAA's website.

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