CHARLOTTE, N.C. — Shocking video shows a positive lightning strike in Myrtle Beach -- it's enough to make any beachgoer nervous. 

The First Warn Storm Team has some tips and information that you should know about thunder and lightning. 

1 out of every 10 lightning strikes will kill somebody, according to Meteorologist Chris Mulcahy. There have been 7 deaths across the United States due to lightning strikes this year so far. 

When you hear thunder, you need to head inside. But it doesn't stop there: stay away from water sources once you are inside -- that includes faucets and showers. Additionally, try to avoid using things that are plugged into an electrical outlet.

"It's amazing how far these lightning bolts can travel," Mulcahy said.

Lightning can travel 20-30 miles. 

When it comes to staying safe, the 30-30 rule helps to protect you during thunderstorms. 

If you hear the sound of thunder 30 seconds after lightning, go indoors. Then remain indoors for 30 minutes after you hear the last time you hear thunder. 

Mulcahy said most people miss a step. When you're counting seconds after you see lightning, it's not as simple as counting "one Mississippi, two Mississippi" and so on. He said after you count the second that you hear thunder on, you have to do a little bit of mental math. 

Sound takes five seconds to travel one mile, Mulcahy said, so you need to divide the seconds by five. For example, if you counted 10 seconds, it's likely only two miles away.

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